Fuel and air

P01CC — Cylinder 1 Injection Timing Over-Advanced

Severity: medium Drive with care, to a shop

What P01CC means

The engine control module monitors when fuel injection actually begins in cylinder 1 and compares it with the commanded timing. P01CC sets when injection occurs too early and the deviation exceeds allowed limits. The usual suspects are the cylinder 1 injector, its control circuit, or fuel supply problems.

Symptoms

  • Check Engine light on
  • Reduced power and sluggish acceleration
  • Rough idle or a misfire feeling
  • Higher fuel consumption
  • Harsh or noisy engine operation
  • Hard starting on some engines

Possible causes

  1. Fault in the cylinder 1 injector control circuit
  2. Failed cylinder 1 injector (electrical or mechanical)
  3. Dirty or sticking fuel injectors
  4. Damaged wiring or poor connection at the injector connector
  5. Fuel pressure or supply problem
  6. Air leak skewing the mixture
  7. ECM calibration issue or engine timing deviation

How to diagnose

  1. Scan all codes and freeze frame data, and look for related injector, misfire or fuel system codes.
  2. Inspect the cylinder 1 injector connector and wiring for corrosion, chafing or damaged insulation.
  3. Review short-term and long-term fuel trims and adaptation values.
  4. Compare cylinders using injector balance and per-cylinder misfire data.
  5. Measure fuel pressure and compare it with the manufacturer's specification.
  6. Test injector resistance and check the drive signal with a scope or multimeter.
  7. Inspect intake and exhaust systems for leaks.
  8. Verify engine timing if everything else checks out.

Common fixes

  • Repair the wiring or replace a damaged connector at the cylinder 1 injector.
  • Clean or replace the cylinder 1 injector.
  • Correct fuel system faults such as pressure, pump or regulator problems.
  • Fix any intake or exhaust leaks.
  • Update or reflash the ECM software if a relevant bulletin exists.

Questions and answers

What does code P01CC mean?

It means the ECM saw fuel injection in cylinder 1 begin too early, beyond the allowed limits. This turns on the check engine light.

Can I drive with P01CC?

Short trips to a shop are usually possible, but don't put it off. The engine may run rough and use more fuel, and a severe deviation could damage the engine.

Where should I start diagnosing P01CC?

Start with the wiring and connector at the cylinder 1 injector, then check fuel trims and fuel pressure. If those are fine, 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.