P020B: Cylinder 2 Injection Timing
What to do
Mention any recent injector work — and if only some injectors were replaced, say which. Diesel injectors carry a calibration code that must be programmed in when they are fitted, and one installed without that step sets exactly this fault.
Note whether the roughness is worse cold or hot, and whether it clears once the engine is warm. That single observation separates an injector problem from a compression or glow plug one on that cylinder.
Ask for the cylinder numbering to be confirmed against the manufacturer's diagram if a part is going to be replaced. It is not always the cylinder you would count to from the front, and on a V engine it is often on the other bank.
What this code means
Injection timing on cylinder 2 is not where the module commanded it to be.
The mechanism is the family's — the module reads each combustion event in the crankshaft's instantaneous speed and compares when the fuel burned against when it asked for it. What varies between members is which cylinder, and that is exactly the diagnostic information the code carries.
Cylinder numbering is where this goes wrong in practice, and it is worth being careful about. Cylinder 2 means the second cylinder in the manufacturer's firing order convention, which is not always the second one you reach from the front of the engine. On a V engine it is frequently on the opposite bank from where a mechanic's intuition puts it. Confirm the numbering against the manufacturer's own diagram before removing anything.
The wrong injector removed is not a harmless mistake on a modern diesel — the calibration code of whatever is disturbed has to be reprogrammed, and the original fault is still there afterwards.
Where cylinder 2 sits next to another cylinder that has also set a timing code, look for what the two share before treating them as separate faults: a common rail pressure sensor, one fuel supply line, or a return circuit feeding both.
Likely causes
Start here
- Failed fuel injector · specialist
- Injector fitted without entering its calibration code · specialist
- Worn or leaking fuel injectors · specialist
Less common
- Low engine compression · specialist
- Injectors swapped between cylinders · specialist
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.
Community experience
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