Fuel and air

P02D3 — Cylinder 4 Injector Offset Learning at Limit

Severity: medium Drive with care, to a shop

What P02D3 means

The engine control unit continually adjusts how long each injector stays open so every cylinder gets the right amount of fuel. P02D3 means the learned correction for cylinder 4 has hit its maximum allowed value, so the ECU can't compensate any further. The injector may be delivering too much or too little fuel, or the mixture in that cylinder is being thrown off by an air leak or fuel supply problem.

Symptoms

  • Check Engine light on
  • Rough idle
  • Misfires or shaking
  • Loss of power and hesitation on acceleration
  • Higher fuel consumption
  • Hard starting (sometimes)

Possible causes

  1. Clogged or failing cylinder 4 fuel injector
  2. Poor connection, corrosion or damage in the injector wiring or connector
  3. Low or unstable fuel pressure (pump, filter or regulator)
  4. Vacuum or intake air leak near cylinder 4
  5. Exhaust leak skewing oxygen sensor readings
  6. Rarely, ECU software or hardware fault

How to diagnose

  1. Scan all codes and freeze frame data, noting any misfire or fuel trim codes
  2. Review short and long term fuel trims and injector learned values
  3. Inspect the cylinder 4 injector connector and harness for damaged pins and bad grounds
  4. Measure injector resistance and check the drive signal with a scope or noid light
  5. Test fuel pressure and delivery volume
  6. Run a cylinder balance test, or swap the injector with a neighbor to see if the fault follows
  7. Check the intake manifold, hoses and gaskets for leaks, and inspect the exhaust
  8. Inspect the spark plug and condition of cylinder 4

Common fixes

  • Clean or replace the cylinder 4 injector
  • Repair the injector wiring or connector
  • Fix fuel delivery issues: replace the filter, pump or regulator
  • Seal the intake air leak or exhaust leak
  • Reset learned values; reflash or replace the ECU only if confirmed faulty

Questions and answers

What does P02D3 mean?

The ECU has used up its adjustment range for the cylinder 4 injector and can't correct fuel delivery any further. It points to an injector, fuel supply or air leak problem.

Can I just clear P02D3?

You can clear it, but it will return if the cause remains. Find what is skewing the mixture first, or you risk misfires and catalytic converter damage.

Do I always need a new injector?

No. Cleaning, a repaired connector, or fixing low fuel pressure or an air leak can solve it. Testing first avoids replacing a good part.

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.