P01CC

What it means

P01CC is a generic powertrain code meaning the engine control unit has found that the injection timing for cylinder 1 is over-advanced, so fuel is being delivered earlier than commanded or than the target. It is mostly seen on diesel engines, where the ECU compares actual and desired start of injection using feedback from sensors and injector data. The exact strategy used to detect this varies by engine and manufacturer.

Symptoms

• Engine management light on
• Diesel knock or rough, noisy running, especially on cold start
• Uneven idle or misfire-like shake
• Loss of power or the car going into limp mode
• Increased smoke or a strong exhaust smell
• Hard starting or extended cranking

Possible causes

• Faulty or sticking cylinder 1 fuel injector (mechanical wear, leakage or incorrect needle response)likely
• Wiring or connector fault in the cylinder 1 injector circuit, such as high resistance, corrosion or chafingpossible
• Crankshaft or camshaft position sensor signal problem leading to incorrect timing referencepossible
• Fuel pressure problem such as a weak high-pressure pump, regulator fault or restricted supplypossible
• Incorrect mechanical engine timing, such as a jumped or incorrectly fitted timing belt or chainrare
• Injector coding or correction values not matching the fitted injector after replacementpossible
• Outdated or faulty ECU calibration, where the manufacturer has issued a fix for this faultrare

How to diagnose

1. Read all stored and pending codes and record the freeze frame data, noting engine temperature, load and speed when the fault set
2. Check for other related codes, for example fuel pressure, position sensor or other cylinder injection timing codes, and deal with those first
3. Inspect the cylinder 1 injector wiring and connector for damage, corrosion, oil contamination and a secure fit
4. Check live data for injection timing, fuel rail pressure actual versus desired, and crank and cam signal correlation
5. Carry out injector tests the manufacturer specifies, such as balance or leak-off checks, comparing cylinder 1 with the others
6. Check the low-pressure fuel supply, including fuel filter condition, fuel quality and any air in the system
7. Check the crank and cam sensor signals and the condition of the timing belt or chain and its timing marks, following the procedure for that engine
8. Confirm injector coding or correction values are correctly stored for the injector fitted to cylinder 1

How to fix

• Repair or replace damaged wiring or connectors in the cylinder 1 injector circuit
• Replace the cylinder 1 injector if testing shows it faulty, then code or adapt it as the manufacturer requires
• Replace a faulty crank or cam position sensor if its signal is out of specification
• Correct fuel supply faults by replacing a blocked filter, repairing air leaks or repairing or replacing the faulty pump or regulator
• Reset the mechanical timing to specification if it is incorrect, and check for any further engine damage
• Apply an ECU software update only if the manufacturer lists it as the fix for this fault

Can I keep driving?

Nearby codes

• P01CBGenericCylinder 1 Injection Timing Performance - Over Retarded
• P01CDGenericCylinder 2 Injection Timing Performance - Over Retarded