Cause
Engine control module replaced or reprogrammed
Not a fault at all, but the loss of everything the module had learned about its own vehicle. A modern engine module accumulates knowledge that no factory could have supplied: injector calibration codes entered per cylinder, injection pump timing and quantity corrections, throttle and pedal end stops, fuel trims built up over thousands of miles, misfire adaptation for this particular crankshaft's manufacturing runout, transmission adaptations, and the vehicle's own identity and immobiliser pairing.
Replacing or reflashing the module discards all of it, and the vehicle then runs on defaults. Defaults feel like wear: hard starting, a harsher note, smoke, uneven idle, poor economy, hesitation. So a car that runs badly immediately after module work presents as a faulty module or a faulty new part, and the natural next step is to replace something else — which changes nothing, because the missing item is data rather than hardware.
The rule worth carrying: a vehicle running badly straight after module work should have its adaptations and calibrations checked before any component is suspected. Restoring them is part of the job, takes minutes with the right equipment, and is the single most common thing left undone.
It is also why disconnecting a battery is not always free. On some vehicles adaptations survive in non-volatile memory; on others they do not, and the car drives differently for a week afterwards while it relearns.
Typically specialist work. Needs equipment or training most home workshops do not have.
Codes this can cause (17)
Codes where this is a likely explanation first, rather than merely a possible one.
- P2176 Throttle Actuator A Control System — Idle Position Not Learned Likely for this code Moderate
- P2673 Injection Pump Timing Calibration Not Learned Likely for this code Moderate
- P2674 Injection Pump Fuel Calibration Not Learned Likely for this code Moderate
- P2B10 Cylinder 1 Injection Pulse Offset Not Learned Likely for this code Moderate
- P2B12 Cylinder 2 Injection Pulse Offset Not Learned Likely for this code Moderate
- P2B14 Cylinder 3 Injection Pulse Offset Not Learned Likely for this code Moderate
- P2B16 Cylinder 4 Injection Pulse Offset Not Learned Likely for this code Moderate
- P2B18 Cylinder 5 Injection Pulse Offset Not Learned Likely for this code Moderate
- P2B1A Cylinder 6 Injection Pulse Offset Not Learned Likely for this code Moderate
- P2B1C Cylinder 7 Injection Pulse Offset Not Learned Likely for this code Moderate
- P2B1E Cylinder 8 Injection Pulse Offset Not Learned Likely for this code Moderate
- P2690 Cylinder 5 Injector Data Incompatible Moderate
- P2691 Cylinder 6 Injector Data Incompatible Moderate
- P2692 Cylinder 7 Injector Data Incompatible Moderate
- P2693 Cylinder 8 Injector Data Incompatible Moderate
- P2694 Cylinder 9 Injector Data Incompatible Moderate
- P2695 Cylinder 10 Injector Data Incompatible Moderate
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
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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