P01CF: Cylinder 3 Injection Timing Performance - Over Retarded
What to do
Ask for a compression test on this cylinder before an injector is replaced, particularly if the car has high mileage. A new injector fitted to a cylinder with poor compression sets the same fault again within days — and that is the most common way this repair goes wrong.
Say whether the engine is much rougher from cold and settles as it warms up. That points at compression or a glow plug rather than the injector, and it is the cheapest thing to establish.
Mention any blue smoke, oil consumption, or a rattle from the engine, all of which support a mechanical rather than fuelling cause.
Expect worse fuel economy while it is unrepaired.
What this code means
Combustion on cylinder 3 is happening later than the module commanded.
Cylinder 3 sits in the hot middle of an inline block, which shapes both of the mechanical causes behind a late burn.
Heat bakes deposits onto the injector nozzle, narrowing the spray holes so the charge atomises coarsely and takes longer to light. And the centre cylinders are the ones whose bores and rings see the highest thermal load, so compression tends to fall there first on a worn engine. Both produce a late burn and both are worse on the cylinder this code names.
Separating them costs nothing and settles the repair.
- A compression test on that cylinder answers the mechanical question directly.
- A cold-start comparison answers it almost as well: low compression is dramatically worse cold and improves as the engine warms, because a warm cylinder seals better and the charge is already hot. A restricted injector behaves the same at any temperature.
Do not skip the compression test on a high-mileage engine just because an injector is the more convenient explanation. A new injector fitted into a cylinder with poor compression sets the same code within days, and that is the failure this code most often leads to.
Glow plug performance is the third candidate and it is cheap to check, though on a warm engine it will not explain a fault that persists.
Likely causes
Start here
- Low engine compression · specialist
- Blocked or restricted injector nozzle · specialist
- Failed fuel injector · specialist
Less common
- Failed glow plug · moderate
- Low fuel pressure · moderate
Symptoms
Components involved
Information, not instruction
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