What does it mean?
During the cold start and warm-up phase the module found that less fuel was actually delivered by the A injection system than it commanded. Cold running has its own fuelling strategy with higher quantities, different injection timing and often several pilot injections, so the module runs a separate check for this phase. When the delivery correction reaches its limit while the engine is still cold and the shortfall lasts long enough, this code is stored rather than the general quantity fault. The distinction is useful, because problems that only appear when the fuel is cold and thick, or when the battery is under cranking load, will not necessarily show up once the engine is warm. Cold weather, poor winter fuel and water in the system are all high on the list here.
Symptoms
- Long cranking before the engine fires, especially on the first start of the day
- Rough running, shaking and white smoke for the first minutes after a cold start
- The engine may start and then stall, requiring a second attempt
- Low power and hesitation until normal operating temperature is reached
- MIL on after the fault repeats over several cold starts
- Normal behaviour once the engine is warm, which often confuses the diagnosis
Likely causes
- Waxed or gelled diesel in cold weather, or summer grade fuel used at low temperature
- Water in the fuel filter or separator, which freezes and restricts flow
- Clogged fuel filter that only restricts enough to matter when the fuel is cold and viscous
- Weak lift or transfer pump that cannot supply enough volume during cranking
- Air drawn into the suction side through a seal that leaks more when cold
- Sticking fuel metering valve that frees up as it warms
- Excessive injector return leakage when cold, so rail pressure builds too slowly
- Low battery or starter voltage during cranking, which reduces pump output
How to fix it
- Ask when the fault occurs and confirm it is limited to cold starts, then plan to test the vehicle after an overnight soak
- Drain the water separator and inspect the filter, including its age and whether winter grade fuel is in the tank
- Measure supply pressure at the high-pressure pump inlet during cranking, not just at idle
- Log actual against desired rail pressure from the first crank so the build-up rate can be seen
- Carry out a cold leak-off test, since return leakage can be much worse before the engine warms
- Check battery condition and cranking voltage, because a weak battery reduces both pump and injector performance
- Inspect the suction side for air ingress with a clear line while cranking
- Replace the component the tests condemn and repeat a cold start with data logging to confirm the repair