Fuel and air

P01D5 — Cylinder 6 Injection Timing Over-Retarded

Severity: medium Drive with care, to a shop

What P01D5 means

The engine control unit compares the actual start of fuel injection on cylinder 6 with the timing it commanded. P01D5 sets when injection starts much later than intended (over-retarded). The usual culprits are the cylinder 6 injector, its wiring, or fuel supply, and less often the control unit itself.

Symptoms

  • Check engine light on
  • Rough idle or vibration
  • Reduced power and sluggish acceleration
  • Higher fuel consumption
  • Possible misfire on cylinder 6
  • Hard starting or unstable idle

Possible causes

  1. Faulty cylinder 6 fuel injector
  2. Clogged or dirty injector
  3. Damaged wiring or poor connection at the injector connector
  4. Low fuel pressure or other fuel supply problem
  5. Air leak skewing the air-fuel mixture
  6. Injection control fault inside the ECM/PCM (rare)

How to diagnose

  1. Scan all codes and freeze frame data, and look for cylinder 6 misfire codes
  2. Review short- and long-term fuel trims at idle and under load
  3. Inspect the cylinder 6 injector connector and harness for corrosion, chafing or breaks
  4. Test the injector circuit: power, ground, coil resistance and control signal with a scope
  5. Compare cylinder balance or per-cylinder contribution
  6. Measure fuel pressure and compare it with the manufacturer spec
  7. Check the intake and vacuum lines for air leaks
  8. Swap the injector with a neighboring cylinder and see whether the fault follows it

Common fixes

  • Replace the faulty cylinder 6 injector
  • Clean a clogged injector
  • Repair or replace injector wiring and connector
  • Fix the cause of low fuel pressure (pump, filter, regulator)
  • Reflash or replace the ECM/PCM only after everything else is ruled out

Questions and answers

What does P01D5 mean?

The engine computer detected that fuel injection on cylinder 6 starts later than it should. The cause is usually the injector, its wiring or the fuel supply.

Can I drive with code P01D5?

Briefly and gently, for example to a shop. If the engine runs rough or the check engine light flashes, don't drive it, because the catalytic converter can be damaged.

How do I fix P01D5?

Start with the cylinder 6 injector connector, wiring and fuel pressure. If those are fine, clean or replace the injector, and suspect the ECM only as a last resort.

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.