What does it mean?
This code says the actual start of injection no longer matches what the control module commanded. On modern common rail diesels the module works out when combustion really began, using crankshaft acceleration, rail pressure behaviour and in some cases a combustion or knock sensor, then compares that with the injection point it asked for. A deviation that persists beyond the allowed window means the fuel is arriving too early or too late in the cycle, which upsets emissions, noise and efficiency. On older systems with a mechanical injection pump the same code covers a timing control valve that cannot hold the commanded advance. Because injection timing has a strong effect on nitrogen oxide and particulate output, the module will often limit power until the deviation is corrected.
Symptoms
- Hard starting, especially when cold, and long cranking times
- Diesel knock and a harsh, noisy combustion sound
- Reduced power and sluggish response, sometimes with limp mode
- Increased smoke from the exhaust, white or grey when timing is retarded
- Rough idle and vibration
- Higher fuel consumption and a possible failure at an emissions inspection
Likely causes
- Worn or leaking injectors whose opening delay has drifted away from their programmed values
- Injector calibration codes not written into the module after a replacement, so the module drives them with the wrong data
- Low or unstable rail pressure caused by a weak high-pressure pump, a restricted filter or a leaking pressure control valve
- Timing chain or belt wear, or a belt that has jumped a tooth, which shifts the whole crank to cam relationship
- Crankshaft or camshaft position sensor signal errors, including a damaged reluctor ring
- Poor fuel quality, water contamination or air in the fuel, which changes how the fuel compresses and burns
- Failed timing control solenoid on engines with a mechanical injection pump
- Wiring faults on injector or timing solenoid circuits
How to fix it
- Check the fuel supply first: filter service history, water separator, and look for air bubbles in a clear return line
- Compare actual and desired rail pressure at idle, under load and during cranking
- Read the injector correction or balance values and see whether one cylinder stands out
- Confirm that the injector calibration codes stored in the module match the codes on the injectors themselves
- Perform a leak-off test to find an injector returning too much fuel
- Check crankshaft and camshaft correlation, timing marks and chain or belt wear, since mechanical timing errors mimic injection faults
- Verify fuel quality and rule out contamination before condemning components
- Repair or renew what the tests condemn, program any new injector codes, then confirm the deviation is gone on a road test