P01CB

What it means

P01CB is a generic powertrain code meaning the engine control unit has found that the injection timing for cylinder 1 is retarded more than it should be. The ECU compares commanded injection timing with what it measures or infers, and sets the code when the difference goes beyond the allowed limit. It is mainly seen on direct injection and diesel engines, and exact detection methods depend on the engine.

Symptoms

• Engine management light on
• Rough idle or misfire on cylinder 1
• Hard starting or extended cranking
• Loss of power or hesitation under load
• Increased smoke, fuel smell or poor fuel economy
• Engine running in a reduced power mode

Possible causes

• Faulty or sticking cylinder 1 fuel injectorlikely
• Wiring or connector fault in the cylinder 1 injector circuit (high resistance, damaged insulation, corrosion)likely
• Low or unstable fuel pressure from a weak high pressure pump, pressure regulator or low pressure supply faultpossible
• Crankshaft or camshaft position sensor signal fault, or timing correlation problempossible
• Incorrect mechanical engine timing, such as a stretched or jumped timing chain or beltpossible
• Outdated or faulty ECU software calibration where the manufacturer has documented it as a causerare
• Internal ECU driver fault for the cylinder 1 injectorrare

How to diagnose

1. Read all stored and pending codes and freeze frame data, noting engine speed, load, temperature and fuel pressure when the fault set
2. Check for related codes covering other injectors, fuel pressure, crank and cam sensors, or misfires, and deal with those first
3. Visually inspect the cylinder 1 injector connector, wiring and earth points for damage, corrosion, oil ingress or chafing
4. Check fuel quality and the low pressure supply, including fuel level, filter condition and supply pressure against specification
5. Compare live data for cylinder 1 against other cylinders, such as injector correction values, balance rates or misfire counters, where the engine supports it
6. Check actual versus commanded fuel rail pressure at idle and under load
7. Test the injector circuit for resistance, supply and control signal following the manufacturer's procedure for that engine
8. Check crank and cam sensor signals and mechanical timing correlation, and check for any available ECU software updates for this model

How to fix

• Repair or replace damaged wiring, terminals or connectors in the cylinder 1 injector circuit
• Replace the cylinder 1 injector if testing shows it is faulty, and code or adapt it as the manufacturer requires
• Correct fuel supply faults, such as a blocked filter, failed lift pump or faulty pressure regulator, or replace a worn high pressure pump
• Replace a faulty crank or cam position sensor, or correct the mechanical timing fault
• Apply a manufacturer calibration update only where a known software issue is documented for the vehicle

Can I keep driving?

Nearby codes

• P01CAGenericFuel Rail Pressure Too Low - Engine Cranking Bank 2
• P01CCGenericCylinder 1 Injection Timing Performance - Over Advanced