Engine & Performance
Fuel System & Injectors
Modern Mercedes injectors are coded, calibrated devices. Fitting one without writing its correction values to the ECU guarantees a rough-running engine.
Signs you need this
- Hard starting, especially when cold or when the tank is low
- Rough idle, misfire, or a diesel knock that got louder
- Black soot around the base of an injector
- Loss of power under load with rail pressure faults stored
How we approach it
We diagnose fuel faults with rail pressure data, injector return-flow testing on diesels, and cylinder-by-cylinder correction values rather than by swapping parts. Common jobs include piezo injector replacement on OM642 and OM651 diesels, high-pressure pump failure on CGI petrol engines, in-tank pump failure across the range, and leaking injector seals that leave black soot around the cylinder head. Every injector we fit is coded to its cylinder.
What the job includes
- 01Rail pressure and fuel delivery testing under load
- 02Injector return-flow (back-leak) testing on diesel engines
- 03Injector removal — including seized injector extraction
- 04New injectors coded to cylinder with correction values written
- 05High-pressure and in-tank fuel pump replacement
- 06Fuel filter service and post-repair adaptation reset
Common questions
Do all the injectors have to be replaced together?
Not always. On diesels with high back-leak we usually recommend a full set because they age at the same rate, but on a petrol engine with one failed injector we are happy to replace only what failed.
My injector is seized in the head — is that a problem?
It is a common one on OM642 diesels and it takes specialist pullers and patience. We do it regularly rather than resorting to removing the cylinder head.
Let us take a look at it.
Call and describe what the car is doing. We will give you an honest assessment before any work begins.
7492 Slater Ave, Huntington Beach, CA 92647 · Mon–Fri 8:00am–5:00pm
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