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Mitsubishi Galant Fortis
2007–2016 (CJ) · 4B11 2.0L MIVEC DOHC · CVT / 6MT
The Mitsubishi Galant Fortis CJ (2007–2016) is a discontinued mid-size sedan still widely maintained in Malaysia. The 4B11 2.0L MIVEC DOHC naturally aspirated engine is reliable. At high mileage, watch for timing belt (NOT chain — this engine uses a belt, replace every 60,000 km), CVT shudder, and power steering rack leaks.
Mitsubishi Galant Fortis Common Problems Malaysia
The Galant Fortis CJ generation is a solid C-segment sedan, but at high mileage Malaysian owners commonly encounter CVT shudder from neglected fluid changes, timing chain rattle from infrequent oil changes, and rocker cover gasket seeps. Carbon buildup on the throttle body is near-universal on units past 80,000 km. Addressing these proactively keeps a discontinued model running reliably for years.
💰Mitsubishi Galant Fortis Repair Cost Malaysia
As a discontinued model, the Galant Fortis generally attracts affordable repair costs at independent workshops compared to newer vehicles. However, some OEM parts are harder to source, which can increase waiting time and cost for specific components. Routine services like oil changes and brake jobs remain competitively priced. For major repairs such as CVT overhaul or timing chain replacement, getting multiple quotes is advisable.
📅Mitsubishi Galant Fortis Service Schedule Malaysia
For the Galant Fortis 4B11 2.0L MIVEC, the key service intervals are: engine oil every 10,000 km, CVT fluid every 40,000 km, spark plugs every 60,000 km, and timing chain inspection at 100,000 km. Many units on Malaysian roads are now at 150,000–200,000 km — if service history is unknown, treat it as overdue across the board and inspect all wear items. A thorough catch-up service can significantly extend the vehicle's useful life.
🛢️Mitsubishi Galant Fortis Engine Oil Malaysia
The Galant Fortis 4B11 2.0L MIVEC DOHC requires fully synthetic engine oil rated API SN or higher, with 0W-20 or 5W-30 viscosity. The sump capacity is approximately 4.7 litres including filter. Change every 10,000 km — the MIVEC variable valve timing system is sensitive to oil quality and cleanliness, so using a high-quality fully synthetic is strongly recommended, especially on high-mileage units where engine internals may have deposits.
⚙️Mitsubishi Galant Fortis Transmission Fluid Malaysia
The Galant Fortis CVT uses Mitsubishi INVECS-III CVT Fluid J1 — do not substitute with a generic CVT fluid, as the wrong fluid can damage the belt and pulleys. The recommended change interval is every 40,000 km, but many high-mileage Malaysian units have never had a fluid change. If the CVT fluid is dark or smells burnt, a gentle drain-and-refill is the safer first step before considering a full flush. Regular fluid maintenance is the single most important factor in CVT longevity on this model.
💨Mitsubishi Galant Fortis Air Filter Replacement Malaysia
The Galant Fortis air filter sits in the airbox on the driver's side of the engine bay and is straightforward to replace. In Malaysian conditions — dusty urban roads and frequent rain — inspect it every 20,000 km and replace when visibly dirty. A clogged air filter reduces throttle response and increases fuel consumption on the 4B11 MIVEC engine. Both OEM-equivalent and quality aftermarket filters are widely available for this model.
🌡️Mitsubishi Galant Fortis Coolant Service Malaysia
The Galant Fortis 4B11 engine uses a standard long-life coolant (LLC). In Malaysia's tropical climate, coolant should be inspected every 40,000 km and replaced every 80,000–100,000 km or if discoloured. High-mileage units should have the cooling system inspected for hose condition, thermostat function, and radiator integrity at the same time. Neglected coolant becomes acidic and can cause internal corrosion to the aluminium engine block and radiator.
🛞Mitsubishi Galant Fortis Brake Pads Malaysia
Brake pad life on the Galant Fortis varies with driving style — city driving in Kuala Lumpur wears pads faster than highway use. Inspect pads every 20,000 km and replace before the wear indicator contacts the disc. The 4B11 Galant Fortis is a moderately weighted sedan, so mid-range semi-metallic or ceramic pads are appropriate for Malaysian conditions. Always replace both pads on the same axle together.
💿Mitsubishi Galant Fortis Brake Disc Malaysia
The Galant Fortis uses vented front discs and solid rear discs. At high mileage, check disc thickness against the minimum specification stamped on the disc — a disc worn below minimum is a safety hazard. Light surface rust on discs is normal after sitting in Malaysian humidity but should clear after a few brake applications. Scored or heavily grooved discs should be replaced rather than skimmed on a high-mileage vehicle where the discs are already worn.
🔵Mitsubishi Galant Fortis Brake Fluid Malaysia
The Galant Fortis requires DOT 3 or DOT 4 brake fluid. Brake fluid is hygroscopic — it absorbs moisture from the air over time, which lowers its boiling point and can cause brake fade under sustained braking. In Malaysia's humid climate, replace brake fluid every two years regardless of mileage. High-mileage units that have never had a fluid change likely have degraded fluid. This is a low-cost service that has a direct impact on braking safety.
🔋Mitsubishi Galant Fortis Battery Replacement Malaysia
Malaysian heat significantly shortens car battery life — expect 2 to 3 years from most batteries in our climate. For the Galant Fortis, a standard 12V car battery in the appropriate group size is required. Signs of a failing battery include slow cranking, dimming lights, and the battery warning light. After fitting a new battery, ensure the ECU and clock settings are reset. Some units may require an idle relearn procedure after battery disconnection.
⚡Mitsubishi Galant Fortis Alternator Malaysia
Alternator issues on a high-mileage Galant Fortis typically present as a battery warning light, dimming headlights at idle, or a discharged battery after short trips. The alternator on the 4B11 is driven by the accessory belt — check belt condition at the same time as any alternator inspection. Remanufactured alternators are available and offer a more cost-effective option than new OEM units for a discontinued model.
❄️Mitsubishi Galant Fortis Air Cond Service Malaysia
A well-functioning air conditioning system is essential in Malaysia, and the Galant Fortis aircon uses R134a refrigerant. Common issues on older units include weak cooling from refrigerant leak, a dirty cabin filter reducing airflow, and a worn compressor clutch on high-mileage examples. Annual servicing — including filter cleaning, condenser wash, and refrigerant top-up check — keeps the system performing well in the heat. Replace the cabin filter at the same time for best results.
🪤Mitsubishi Galant Fortis Cabin Filter Malaysia
The cabin air filter on the Galant Fortis is located behind the glove box and filters dust, pollen, and pollutants from entering the cabin. In Malaysian conditions — with haze seasons and dusty roads — replace it every 15,000–20,000 km or annually. A clogged cabin filter reduces aircon airflow and can cause musty odours inside the car. Activated carbon cabin filters are available for this model and are a worthwhile upgrade for daily drivers.
🔄Mitsubishi Galant Fortis Tyre Guide Malaysia
The standard tyre size for the Galant Fortis is 215/45R17 for Sport and Sportback variants, with the Elegance running 205/60R16. In Malaysia's wet climate, wet-weather grip and aquaplaning resistance should be priority factors. Mid-range tyres from Bridgestone, Continental, or Michelin offer a good balance of comfort, grip, and cost for this C-segment sedan. Check tyre age as well as tread depth — tyres older than 5 years should be replaced regardless of remaining tread.
🎯Mitsubishi Galant Fortis Wheel Alignment Malaysia
Wheel alignment on the Galant Fortis should be checked every 10,000 km or whenever new tyres are fitted, or after hitting a significant pothole — common on Malaysian roads. Misalignment causes uneven tyre wear and can make the car pull to one side. On high-mileage units, worn suspension bushings and ball joints can cause alignment to drift even after adjustment — inspect these components before performing alignment for best results.
🔥Mitsubishi Galant Fortis Spark Plugs Malaysia
The 4B11 engine uses 4 iridium spark plugs, with a replacement interval of every 60,000 km. NGK or Denso iridium plugs are the recommended equivalents. Given that most Galant Fortis units on Malaysian roads in 2025 are well over 100,000 km, check your service history — if spark plugs were never replaced or replaced with standard plugs, they are likely overdue. Worn plugs on a high-mileage MIVEC engine can cause misfires, rough idle, and increased fuel consumption.
⛓️Mitsubishi Galant Fortis Timing Chain Malaysia
The 4B11 engine uses a timing chain rather than a belt, which is more durable but not maintenance-free. On high-mileage units — especially those where oil changes were not performed on schedule — the VVT actuator and chain tensioner can show wear, leading to a rattling noise on cold starts. Inspect the timing chain system at 100,000 km service. Persistent cold-start rattle should be diagnosed promptly, as a stretched chain or worn tensioner can ultimately cause timing deviation and engine damage.
🧹Mitsubishi Galant Fortis Carbon Buildup Malaysia
The 4B11 uses port fuel injection, which means intake valves receive fuel wash on every cycle — making it less prone to severe intake valve carbon buildup than direct-injection engines. However, throttle body carbon accumulation remains common at 60,000–80,000 km. High-mileage units almost certainly need a throttle body clean. Symptoms include hesitation on light throttle, a rough idle, and a slight dip in fuel economy. Cleaning is straightforward and can restore throttle response noticeably.
🔩Mitsubishi Galant Fortis Engine Mount Malaysia
Engine mounts on a high-mileage Galant Fortis are commonly worn by the time the car reaches 150,000 km. Symptoms include increased cabin vibration at idle, a thud when engaging drive or reverse, and engine movement visible when revving. The 4B11 has hydraulic engine mounts that degrade with age and heat. Replacing worn engine mounts improves cabin refinement noticeably and prevents stress on surrounding components like the driveshaft and exhaust.
🏎️Mitsubishi Galant Fortis Suspension Service Malaysia
Malaysian road conditions — potholes, speed bumps, and uneven surfaces — accelerate suspension wear on the Galant Fortis. On units with over 150,000 km, expect worn shock absorbers, deteriorated rubber bushings, and potentially loose ball joints. Signs of suspension wear include a bouncy ride, clunking sounds over bumps, and uneven tyre wear. A full suspension inspection should be carried out alongside wheel alignment. Replacing worn shocks and bushings transforms ride quality significantly.
💻Mitsubishi Galant Fortis Computer Diagnostic Malaysia
The Galant Fortis CJ uses a standard OBD-II diagnostic port, accessible to most generic scan tools. However, for deeper diagnostics — including INVECS-III CVT data, MIVEC timing data, and ABS/SRS codes — a Mitsubishi-specific scanner or professional diagnostic tool provides far more detail than a generic reader. If the check engine light is on, a diagnostic scan is the starting point for any repair. Don't clear codes without understanding the underlying fault first.
🔔Mitsubishi Galant Fortis Service Indicator Malaysia
The Galant Fortis does not have a sophisticated oil life monitoring system — it relies on a simple mileage-based service reminder. The maintenance light typically illuminates at set mileage intervals and can be reset via the instrument cluster. Do not rely solely on the indicator for oil change timing; follow the 10,000 km interval using a trip meter or logbook. For high-mileage vehicles, tracking service intervals manually and keeping a simple logbook is highly recommended.
💧Mitsubishi Galant Fortis Oil Leak Malaysia
Oil leaks are common on high-mileage Galant Fortis units as rubber seals and gaskets age in Malaysia's heat. The most frequent sources include the rocker cover gasket, camshaft seals, and the crankshaft front and rear seals. A minor seep that only leaves a small spot on the driveway is less urgent, but any leak that is dripping actively should be addressed promptly to avoid oil loss and fire risk. The rocker cover gasket is the most common and accessible fix on this engine.
🕹️Mitsubishi Galant Fortis Power Steering Malaysia
The Galant Fortis uses an Electric Power Steering (EPS) system, which eliminates the need for power steering fluid and a hydraulic pump. This is generally reliable, but on high-mileage units, EPS issues can manifest as increased steering effort, a steering wheel that vibrates, or an EPS warning light on the dashboard. EPS faults are often electrical — check the EPS fuse, battery condition, and scan for EPS fault codes before assuming the steering rack or motor requires replacement.
⛽Mitsubishi Galant Fortis Fuel Economy Tips Malaysia
The Galant Fortis 4B11 2.0L returns reasonable fuel economy when properly maintained — the CVT helps keep the engine in its efficient range. To maximise economy: keep tyres inflated to the recommended pressure, replace spark plugs on schedule, ensure the throttle body is clean, and avoid excessive idling in traffic. A dirty air filter or worn spark plugs can noticeably reduce efficiency. On a high-mileage unit, a full tune-up often restores near-original fuel economy.
📈Mitsubishi Galant Fortis Resale Value Malaysia
The Galant Fortis has depreciated significantly as a discontinued model — it now sits in the budget used-car segment in Malaysia. This means resale value is low, but it also makes it accessible for buyers wanting a well-sized Japanese sedan at an affordable price. For sellers, mechanical condition matters far more than cosmetics: a car with documented service history, working aircon, and no CVT issues commands a meaningfully better price than one with deferred maintenance. Good time to buy a cheap runner if you don't mind servicing it.
✅Mitsubishi Galant Fortis Used Car Checklist Malaysia
When buying a used Galant Fortis, the most critical checks are: CVT condition (test drive for shudder or hesitation, especially in hot weather), timing chain noise on cold start, any oil leaks visible under the car, and whether the service history is documented. Many high-mileage units in the market have unknown histories. Have a mechanic perform a pre-purchase inspection — the cost is small relative to inheriting a car with a worn CVT or neglected timing chain.
📖Mitsubishi Galant Fortis Generations Guide Malaysia
Only the CJ generation (2007–2016) was sold in Malaysia. Malaysian variants included the 2.0 Elegance (16-inch wheels, more conservative trim), 2.0 Sport (17-inch wheels, sport trim), and the 2.0 Sportback — a practical fastback hatchback variant on the same platform. The Ralliart variant with the turbocharged 4B11T engine was extremely rare in Malaysia and commands more attention for its performance parts. All variants use the same 4B11 2.0L MIVEC base engine, making parts largely interchangeable between Elegance and Sport.
⛽Mitsubishi Galant Fortis Fuel Pump Malaysia
The Galant Fortis uses an in-tank electric fuel pump. A failing fuel pump typically causes hard starting, loss of power at high load, stalling, or a whining noise from the fuel tank area. On high-mileage units, particularly those that have frequently run on a low fuel level (which reduces the cooling effect on the pump), the fuel pump can wear prematurely. Quality aftermarket pumps are available for this model. Replace the fuel filter at the same time if accessible.
🔧Mitsubishi Galant Fortis Fuel Injector Malaysia
The 4B11 uses port fuel injectors, which are more resistant to coking than direct injection injectors. However, on high-mileage units using lower-quality fuels, injector deposits can build up and affect spray pattern. Symptoms include rough idle, slight hesitation, and a drop in fuel economy. Ultrasonic injector cleaning is a cost-effective service before committing to replacement. If one injector is significantly more clogged than others, individual replacement is an option.
🌡️Mitsubishi Galant Fortis Radiator Malaysia
Radiator issues on a high-mileage Galant Fortis are typically caused by aging coolant that has become acidic, corroding the aluminium core, or by a physically damaged radiator from an impact. Signs of a failing radiator include overheating, coolant puddles under the car, and milky coolant (indicating head gasket involvement). Prevention is key: maintain clean coolant on schedule. Aluminium radiator replacements are available for this model at reasonable cost.
🌡️Mitsubishi Galant Fortis Thermostat Malaysia
The thermostat regulates engine operating temperature on the Galant Fortis — a thermostat that is stuck open results in the engine never reaching normal operating temperature (reducing efficiency and increasing wear), while one stuck closed causes overheating. On a high-mileage unit, the thermostat is a relatively low-cost item to proactively replace during cooling system service. If your temperature gauge takes unusually long to rise or rarely reaches the midpoint, suspect the thermostat.
⚠️Mitsubishi Galant Fortis Head Gasket Malaysia
Head gasket failure on the Galant Fortis 4B11 is not common if the cooling system has been maintained, but it becomes a risk on high-mileage units that have suffered overheating events. Signs include white smoke from the exhaust, milky engine oil, coolant consumption without visible leaks, and bubbling in the coolant reservoir. A head gasket repair is a significant undertaking — on a high-mileage, low-value vehicle, owners should weigh repair cost against vehicle value carefully before proceeding.
🔩Mitsubishi Galant Fortis CV Joint Malaysia
CV joints on the Galant Fortis are protected by rubber CV boots. The most common failure mode is a torn CV boot, which allows grease to escape and dirt to enter, accelerating joint wear. Listen for a clicking sound on full-lock turns — this is a classic symptom of a worn outer CV joint. On high-mileage units, inspect CV boots at every service. Replacing a torn boot early is far cheaper than replacing the entire CV axle after the joint has worn.
🪟Mitsubishi Galant Fortis Window Regulator Malaysia
Window regulator failures are a known wear item on older vehicles in Malaysia's humid climate. On the Galant Fortis, a faulty window regulator typically causes the power window to move slowly, stop midway, or stop functioning entirely. The front windows — used most frequently — are more susceptible to wear. Replacement regulators are generally available for this model. The driver's front window regulator is the most commonly replaced unit.
🔴Mitsubishi Galant Fortis Check Engine Light Malaysia
A check engine light on the Galant Fortis can indicate a wide range of issues — from a loose fuel cap to a faulty oxygen sensor, MIVEC solenoid issue, or catalytic converter efficiency fault on high-mileage units. An OBD-II scan will retrieve the specific fault code. Do not ignore a solid check engine light, and never drive with a flashing check engine light (which indicates an active misfire that can damage the catalytic converter). On a high-mileage unit, O2 sensor faults are among the most common causes.
🚨Mitsubishi Galant Fortis ABS Warning Light Malaysia
An illuminated ABS warning light on the Galant Fortis means the ABS system has detected a fault and is temporarily disabled — normal braking still functions, but the anti-lock feature will not activate. The most common causes on high-mileage units are a faulty wheel speed sensor (often caused by a damaged sensor ring or corroded connector) or a failing ABS pump. Diagnose with a proper scan tool before replacing parts. Wheel speed sensor replacement is usually straightforward and inexpensive.
📋Mitsubishi Galant Fortis 100,000 km Service Malaysia
The 100,000 km service is a major milestone for the Galant Fortis. Key items to address: spark plug replacement (iridium, 4 pcs), timing chain and VVT actuator inspection, CVT fluid change (if not done within the last 40,000 km), full brake system inspection, suspension and bushing check, coolant replacement, and throttle body cleaning. Many units on Malaysian roads are now at 150,000–200,000 km — if the car has no service history, performing a comprehensive catch-up service is the right starting point before addressing any specific faults.
📄Mitsubishi Galant Fortis Insurance Cost Malaysia
Insurance premiums for the Galant Fortis are generally low due to its depreciated market value. For older units with low market value, an Agreed Value (AV) policy may be worth considering to ensure a defined payout in case of total loss — the market value of such an old model can be unpredictably low at claims time. Compare comprehensive versus third-party cover: for a low-value vehicle still used daily, comprehensive cover often still makes sense to protect against accident repair costs.
💰Mitsubishi Galant Fortis Spare Parts Price Malaysia
As a discontinued model, some OEM Galant Fortis parts are becoming harder to source in Malaysia — particularly body panels, interior trim pieces, and certain electronics. Mechanical wear items like brake pads, filters, belts, and suspension components are generally available through aftermarket suppliers. CVT-related parts and MIVEC solenoids can be harder to find and more expensive. Always confirm parts availability before committing to a major repair, and check with specialist Mitsubishi parts suppliers.
✅Mitsubishi Galant Fortis Puspakom Inspection Guide Malaysia
For Puspakom B2 or B5 inspections (required for ownership transfers), the Galant Fortis needs to pass checks on lights, brakes, steering, tyres, and structural condition. On a high-mileage unit, ensure there are no visible oil leaks on the underside, the handbrake holds correctly, all lights function, and tyres are within legal tread depth. Fix obvious defects before the inspection rather than attempting a re-inspection. Suspension and brake system condition are key focus areas for older vehicles.
💧Mitsubishi Galant Fortis Rocker Cover Gasket Malaysia
Rocker cover gasket seeps are among the most common oil leak complaints on high-mileage Galant Fortis units. The rubber gasket hardens and shrinks with age and heat, leading to oil seeping at the top of the engine. A telltale sign is an oily film or dried oil residue around the valve cover. If left unattended, oil can drip onto hot exhaust components. The 4B11 rocker cover gasket is an accessible repair — parts are reasonably priced and the job does not require major disassembly.
🔧Mitsubishi Galant Fortis Throttle Body Cleaning Malaysia
Throttle body carbon buildup is a predictable maintenance item on the Galant Fortis at 60,000–80,000 km intervals. Deposits on the throttle plate and bore restrict airflow at small throttle openings, causing hesitation on tip-in, a slightly rough idle, and reduced fuel economy. Cleaning involves removing the throttle body and using a dedicated throttle body cleaner. After cleaning, the car may require an idle relearn procedure. This is a straightforward service with a noticeable improvement in driveability.
💡Mitsubishi Galant Fortis Headlight Upgrade Malaysia
The Galant Fortis CJ came with halogen headlights as standard. Over time, the polycarbonate headlight lenses yellow and haze, significantly reducing light output. Options for owners include: headlight lens restoration (polishing), direct LED bulb replacement for improved brightness, or sourcing a projector lens upgrade. Ensure any LED upgrade uses proper heat-dissipating bulbs designed for automotive use, and that beam pattern does not dazzle oncoming traffic — this is a legal requirement in Malaysia.
🔄Mitsubishi Galant Fortis Tyre Rotation Malaysia
Tyre rotation on the Galant Fortis should be performed every 10,000 km to ensure even wear across all four tyres. As a front-wheel-drive vehicle, the front tyres carry the additional load of steering and power delivery, causing them to wear faster than the rears. Rotating tyres extends the life of a full set. Always check and adjust tyre pressure after rotation. Combine rotation with a wheel alignment check for best results, especially on high-mileage units where uneven wear patterns may have developed.
🌧️Mitsubishi Galant Fortis Wiper Replacement Malaysia
Wiper blades degrade quickly in Malaysia's climate — UV exposure and frequent use during monsoon season typically mean replacement is needed every 6–12 months. The Galant Fortis uses hook-type wiper arm fittings, and both OEM-equivalent and frameless beam wipers are compatible. Frameless beam wipers conform better to the curved windscreen and resist clogging with dirt. Replace both front wipers at the same time. Also check rear wiper condition on the Sportback variant.
🔍Mitsubishi Galant Fortis Oxygen Sensor Malaysia
The Galant Fortis 4B11 uses upstream and downstream oxygen (O2) sensors to manage fuel trim and monitor catalytic converter efficiency. On high-mileage units, O2 sensor degradation is common and often triggers P0130–P0161 type fault codes and the check engine light. A faulty upstream O2 sensor can cause rich or lean running, increased fuel consumption, and rough idle. Use an OBD-II scanner to confirm which sensor has failed before replacement. NGK and Denso replacements are available and reliable for this application.
🔩Mitsubishi Galant Fortis Suspension Arm Malaysia
The Galant Fortis uses a multi-link rear suspension setup, with front MacPherson struts. Suspension arm bushings and ball joints are wear items that deteriorate over time, particularly on Malaysian roads with frequent bumps and potholes. Worn bushings cause vague steering, excessive body roll, and noise over bumps. On units approaching or past 150,000 km, a suspension arm inspection is prudent. Bushing-only replacement can be done if the arm itself is undamaged; otherwise, replacing the complete arm assembly is often more practical.
🗂️Mitsubishi Galant Fortis Workshop Case Studies Malaysia
Four real-world repair cases from 4M Car Care workshop in Malaysia highlight the most common high-mileage Galant Fortis issues: Case 1 — CVT Shudder from Neglected Fluid: A 2011 Galant Fortis with 178,000 km came in with severe CVT shudder during low-speed acceleration. The CVT fluid was dark brown with a burnt smell — the original fluid had never been changed. A cautious two-stage drain-and-refill with genuine INVECS-III CVT Fluid J1 improved the shudder significantly, though the owner was advised that some shudder may persist due to wear on the CVT belt from years of degraded fluid. Case 2 — Timing Chain Rattle from Neglected Oil Changes: A 2009 Galant Fortis Sport at 193,000 km presented with a prominent cold-start rattle lasting 5–10 seconds before quieting. Diagnostic scan showed no codes, but oil condition was very poor. The VVT oil control solenoid had a partially blocked filter screen. After a sump clean, fresh 0W-20 synthetic oil, and VVT solenoid screen cleaning, the cold-start rattle reduced substantially. The chain tensioner was inspected and found to be at the limit of its adjustment range — the owner was counselled on monitoring and budgeting for future chain replacement. Case 3 — Rocker Cover Gasket Seep with Spark Plug Well Flooding: A 2013 Galant Fortis Elegance at 142,000 km showed oil seeping from the rocker cover and pooling in the spark plug wells — a known failure mode when the gasket and plug well O-rings both degrade simultaneously. The rocker cover gasket and all four spark plug well O-rings were replaced at the same time as a scheduled iridium spark plug change. Post-repair, the owner reported noticeably improved idle quality — the spark plug wells had been contaminated with oil, causing intermittent misfires. Case 4 — Throttle Body Carbon Causing Hesitation: A 2010 Galant Fortis Sport at 115,000 km arrived with the owner complaining of a stumble on light throttle opening — most noticeable when pulling out of junctions. OBD scan showed no active codes. Throttle body inspection revealed heavy carbon deposits restricting the bore. A full throttle body removal and ultrasonic clean, followed by an idle relearn procedure, completely resolved the hesitation. The owner had no record of any previous throttle body service.