This Mercedes C-Class came in with an engine misfire. XENTRY found fault codes pointing to the fuel injectors. We replaced all four, road tested the car, and the owner confirmed: no misfire.
Job completed: September 2026
| Car | Mercedes-Benz C-Class, about 251,000km |
|---|---|
| Symptom | Engine misfire |
| Fault found | XENTRY fault codes P030085 and P030385: cylinder misfire traced to the fuel injectors |
| Repair done | All four fuel injectors replaced with OEM-grade parts, valve cover removed for access, road tested after |
| Parts | OEM-grade fuel injectors |
| Time taken | Timeline confirmed when you book |
| Cost | Quoted and approved before work began |
| Warranty | Road tested before handover |
The owner brought in this Mercedes C-Class with an engine misfire. The car was at about 251,000km, which is high mileage for a direct-injection petrol engine.
A misfire is hard to ignore. The engine runs rough, feels hesitant under load, and can trigger the check engine light. Left undiagnosed, it puts strain on the catalytic converter and can lead to a bigger repair bill. The owner wanted to know what was causing it and whether it could be fixed properly.
This is a Mercedes-Benz C-Class, the W205 generation, champagne in colour. At about 251,000km on the clock it has done well, but high-mileage direct-injection engines can develop fuel injector faults over time.
The W205 C-Class uses direct fuel injection, where the injectors spray fuel directly into the combustion chamber at high pressure. Direct injection delivers better efficiency and power, but it also puts the injectors under more stress than older port-injection systems. Over time, carbon deposits and wear affect how well each injector atomises the fuel, and a failing injector will cause a cylinder to misfire.
We connected XENTRY, the Mercedes-Benz factory diagnostic system, and scanned the engine control module.
Two fault codes came up immediately: P030085 and P030385. Both are cylinder misfire codes, indicating that the engine control module had detected abnormal combustion events on specific cylinders. The fault codes pointed clearly to the fuel injectors.
We checked the rest of the engine systems and found nothing else flagged. The diagnosis was straightforward: the injectors needed to be replaced.
Direct fuel injectors work at high pressure and temperature, every engine cycle, for the life of the car. At high mileage the internal components wear, and the nozzle tip that sprays fuel into the cylinder can foul with carbon deposits.
When an injector cannot spray fuel cleanly, the air-fuel mixture in that cylinder becomes uneven. Combustion is incomplete, and the engine control module sees it as a misfire. On a car with over 250,000km, it is not unusual for all four injectors to be at the end of their service life at roughly the same time.
The XENTRY fault codes gave us the evidence to confirm the cause without guesswork.
Because the fault codes pointed to the injectors and not to other engine systems, the repair was targeted: replace all four fuel injectors.
The owner collected the car and confirmed: no misfire.
From our team's record of this job. Number plates are pixelated.
The cost depends on the number of injectors replaced and the car model. On this C-Class we replaced all four at once, which is the more cost-effective approach when all injectors are at the same high mileage and the fault traces back to the fuel system.
We quote before any work begins. WhatsApp us your car model and mileage and we will give you an honest figure.
On a direct-injection engine, keeping the fuel system clean helps injectors last longer. Using quality fuel and following the manufacturer's service intervals for fuel system maintenance keeps the injectors in better condition.
The more important step is acting when you first notice a misfire or a check engine light. A misfire that is caught early is typically just an injector job. One that is ignored for months can damage the catalytic converter, which is a much more expensive part to replace.
If your Mercedes C-Class has high mileage and starts to feel rough, get it scanned with XENTRY before the problem grows.
This Mercedes-Benz C-Class (Fuel injector replacement) was handled at 1 Car Service, an independent workshop in Sin Ming AutoCity, Singapore. For Mercedes-Benz, we use dealer-level XENTRY diagnostics. We hold a 4.9★ rating from 1,817+ Google reviews.
WhatsApp us your car model and mileage. We plug in XENTRY, find the real fault code, and quote every item before any work starts. Road tested before you collect.
The cost depends on how many injectors are replaced and the specific model. On high-mileage cars it often makes sense to replace all injectors at once, since they have done the same number of kilometres. We quote before any work begins, so WhatsApp us your model and mileage for an honest figure.
Yes, if the rest of the engine is healthy. A fuel injector job restores smooth combustion and protects the catalytic converter, which is far more expensive to replace. On this car at about 251,000km the engine was otherwise sound, so replacing the injectors was the right repair. We always confirm what else needs attention before quoting.
We connect XENTRY, the Mercedes-Benz factory diagnostic system, and read the fault codes from the engine control module. Cylinder-specific misfire codes like P030085 and P030385 point directly to injector faults. We back up the scan with a road test to confirm the symptom before any parts are ordered.
Yes. XENTRY is the Mercedes-Benz factory diagnostic system and it is what we use on every Mercedes that comes in. It reads the same fault codes and live data that a Mercedes dealer uses, so we get the same depth of diagnosis without the dealership bill.
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