Fuel and air

P01D3 — Cylinder 5 Injection Timing Over-Retarded

Severity: medium Drive with care, to a shop

What P01D3 means

The engine control unit compares the commanded and actual start of fuel injection for cylinder 5. P01D3 sets when injection happens much later than requested, meaning it is over-retarded. It is mostly seen on electronically controlled diesel injection systems, where injection timing is critical for clean combustion.

Symptoms

  • Check Engine light on
  • Rough running or misfire on cylinder 5
  • Reduced power and poor acceleration
  • Higher fuel consumption
  • Exhaust smoke, especially during cranking
  • Hard or long starting

Possible causes

  1. Faulty or worn cylinder 5 fuel injector
  2. Bad crankshaft or camshaft position signal affecting timing calculation
  3. Low fuel pressure from a weak pump, clogged filter or rail problem
  4. Wiring or connector fault at the injector (open, corrosion, poor contact)
  5. PCM software or learned adaptation error
  6. Air leak in the fuel system or intake

How to diagnose

  1. Read all codes and freeze-frame data, noting any other injector or sensor codes
  2. Review fuel trims and per-cylinder adaptation values and compare cylinder balance
  3. Test fuel pressure, including rail pressure, and inspect the fuel filter
  4. Inspect the cylinder 5 injector harness and connector, then check circuit continuity, power and ground
  5. Check crankshaft and camshaft sensor signals with a scope
  6. Compare injector performance with neighbors (cutout test, return flow test)
  7. Look for air leaks in the intake and fuel lines

Common fixes

  • Replace the faulty cylinder 5 injector
  • Clean or service the injectors
  • Replace the fuel filter and fix the cause of low pressure
  • Repair the wiring or connector
  • Update PCM software and perform injector adaptation

Questions and answers

What does P01D3 mean?

The control unit detected fuel injection in cylinder 5 starting later than commanded. The usual culprits are the injector, fuel pressure, position sensors or wiring.

Can I drive with P01D3?

Briefly and carefully, only until it can be repaired. It can cause misfires, power loss and smoke, and over time may harm the catalyst or particulate filter.

How do I clear P01D3?

Clearing the code only helps temporarily. Find the cause first by checking the injector, fuel pressure and wiring, then erase the code with a scan tool.

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.