Fuel and air

P01CF — Cylinder 3 Injection Timing Over-Retarded

Severity: medium Drive with care, to a shop

What P01CF means

The engine control unit compares the actual start of injection in cylinder 3 with the calculated target and finds it too late, beyond the allowed tolerance. Injection timing depends on the electrical pulse to the injector and on fuel rail pressure. If the injector opens late, pressure is unstable or the circuit has extra resistance, the ECU stores this code and turns on the check engine light.

Symptoms

  • Check engine light on
  • Rough idle
  • Reduced power and sluggish acceleration
  • Hesitation or stumbling under load
  • Higher fuel consumption
  • Possible misfire on cylinder 3

Possible causes

  1. Cylinder 3 injector opening late, clogged or worn
  2. Low or unstable fuel rail pressure
  3. Damaged wiring or corroded connector in the injector circuit
  4. Intake air leak skewing the mixture
  5. Weak fuel pump, faulty pressure regulator or clogged fuel filter
  6. ECU software or calibration problem (less common)

How to diagnose

  1. Read all codes and freeze frame data and look for related misfire codes
  2. Review fuel trims and mixture adaptation values, especially for cylinder 3
  3. Compare cylinder balance or per-cylinder corrections with a scan tool
  4. Inspect the cylinder 3 injector connector and harness, and test the power and control circuits
  5. Measure injector resistance and check the control pulse with a scope
  6. Measure fuel pressure at idle and under load
  7. Check the intake and exhaust for leaks
  8. Swap the injector with a neighbor and see whether the fault follows it

Common fixes

  • Clean or replace the cylinder 3 injector
  • Repair the wiring or replace the damaged connector
  • Replace the fuel filter, pump or pressure regulator if pressure is low
  • Fix any intake air leaks
  • Update the ECU software if the manufacturer has a service update

Questions and answers

What does P01CF mean?

The ECU detected that fuel injection in cylinder 3 starts later than the calculated timing. The usual culprits are the injector, fuel pressure or wiring.

Can I drive with P01CF?

Only briefly and gently, to reach a shop. If the engine misfires, jerks or the check engine light flashes, stop driving to protect the catalytic converter.

Where should I start diagnosing P01CF?

Start with fuel trim data and a check of the cylinder 3 injector connector and wiring, then measure fuel pressure and test the injector itself.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.