Fuel and air

P01D4 — Cylinder 5 Injection Timing Over-Advanced

Severity: medium Drive with care, to a shop

What P01D4 means

P01D4 sets when the actual start of fuel injection in cylinder 5 comes earlier than the timing the engine control module commands. The ECM normally compares commanded and actual timing and corrects any small difference. When the error exceeds the allowed limit, it stores the code and turns on the check engine light.

Symptoms

  • Check engine light on
  • Rough idle
  • Hesitation or weak acceleration
  • Misfire on cylinder 5
  • Higher fuel consumption
  • Harsh running or knocking noise
  • Possible exhaust smoke

Possible causes

  1. Faulty or sticking fuel injector on cylinder 5
  2. Incorrect timing calculation from an ECM fault or outdated software
  3. Damaged wiring, corroded or loose connector at the injector
  4. Low or unstable fuel pressure (pump, regulator, lines)
  5. Air leak shifting the mixture
  6. Crankshaft or camshaft position sensor problems affecting timing reference

How to diagnose

  1. Scan all codes and freeze frame data, and note any other injection or misfire codes
  2. Review fuel trims and mixture adaptation values at idle and under load
  3. Compare cylinder balance or per-cylinder corrections to see if cylinder 5 stands out
  4. Test fuel pressure and its stability against the manufacturer spec
  5. Inspect the cylinder 5 injector connector and harness, and test circuit continuity and injector resistance
  6. Look for intake air leaks and exhaust leaks ahead of the oxygen sensors
  7. Check crankshaft and camshaft sensor signals
  8. Check for an ECM software update for your vehicle

Common fixes

  • Replace or service the cylinder 5 injector
  • Repair the injector wiring or connector
  • Fix the fuel system fault: pump, pressure regulator, lines or filter
  • Repair intake air leaks
  • Update or reflash the ECM software

Questions and answers

What does P01D4 mean?

It means fuel injection in cylinder 5 starts earlier than the ECM commands. The usual culprits are the injector, its wiring or fuel pressure.

Can I drive with P01D4?

Only briefly and carefully, to get it diagnosed. If the engine knocks, shakes badly or loses power, pull over, since prolonged early injection can damage the engine.

How do I fix P01D4?

Start with the cylinder 5 injector, its wiring and fuel pressure. If those are fine, check the timing sensors and look for an ECM software update.

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.