P01D6: Cylinder 6 Injection Timing Performance - Over Advanced
What to do
Ask two questions before agreeing to any work: how many cylinders are affected, and in which direction. One cylinder means that injector. All of them means something shared, like fuel or timing. A mixture of early and late usually means the injector calibration codes are mismatched — which is corrected with a laptop rather than with parts.
Say whether the engine knocks or sounds harsh under load, which fits this fault.
If an injector must be replaced, ask for the leak-back figures on all six and the labour to reach them. Doing a worn set together is considerably cheaper than one at a time on a six-cylinder engine.
Do not run it like this indefinitely, since early combustion loads the piston and bearings at the wrong point in the stroke.
What this code means
Combustion on cylinder 6 is happening earlier than the module commanded.
This is the last member of the family, and it is a reasonable place to record what the eleven codes are worth read together rather than one at a time.
The direction tells you the mechanism. Retarded means something is slowing the burn — a late-opening or restricted injector, low compression, a dead glow plug, low rail pressure. Advanced means something is starting it early — a leaking injector, an inaccurate pilot injection, over-volatile fuel, or a hot spot.
The distribution tells you the scope. One cylinder is local. All cylinders together is shared hardware — the timing drive, rail pressure, or the fuel in the tank. A mixture of both directions across several cylinders is mismatched calibration codes, which is a laptop fix rather than a parts bill.
Those two questions — which direction, and how many cylinders — narrow this family faster than any test, and both are answered from the stored codes before anything is touched.
For this code specifically, on a straight six, the far-end position that makes its retarded sibling a chain suspect makes this one an injector suspect: chain stretch retards, it does not advance. So an over-advanced code on the last cylinder points back at that injector or its pilot delivery rather than at the timing drive.
Access and labour dominate the decision on a six, so ask for the whole set's figures before committing to one injector.
Likely causes
Start here
- Worn or leaking fuel injectors · specialist
Less common
- Injector fitted without entering its calibration code · specialist
- Carbon deposits in the combustion chamber · specialist
- Contaminated or poor quality fuel · moderate
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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