Fuel and air

P02D4 — Cylinder 5 Injector Offset Learning at Minimum Limit

Severity: medium Drive with care, to a shop

What P02D4 means

The engine control module continually learns a small correction for each injector so every cylinder gets an equal amount of fuel. P02D4 means the correction for cylinder 5 has hit its minimum limit and the ECM cannot reduce fuel any further. This usually points to an injector delivering too much fuel or a rich condition in that cylinder.

Symptoms

  • Check Engine light on
  • Rough idle or vibration
  • Loss of power or sluggish acceleration
  • Higher fuel consumption
  • Misfire on cylinder 5
  • Fuel smell or black smoke from the exhaust

Possible causes

  1. Leaking, sticking or carbon-fouled injector on cylinder 5
  2. Mechanical injector fault such as a worn nozzle or stuck needle
  3. Damaged wiring or connector at the injector
  4. Fuel pressure that is too high (regulator or return problem)
  5. Faulty sensors affecting mixture, such as the O2 sensor or MAF sensor
  6. ECM software fault or outdated calibration

How to diagnose

  1. Scan for all codes and freeze-frame data, noting any other injector or fuel trim codes
  2. View fuel trims and per-cylinder learned injector values on a scan tool
  3. Check cylinder balance and misfire counts for cylinder 5
  4. Inspect the injector connector and wiring, and measure injector resistance
  5. Measure fuel pressure and confirm it is not above spec
  6. Pull the cylinder 5 spark plug; heavy fouling or a fuel smell points to an over-fueling injector
  7. Verify O2 sensor and MAF sensor readings
  8. Swap the injector with a neighbor to see whether the fault follows it

Common fixes

  • Clean or replace the cylinder 5 injector
  • Repair the injector wiring or connector
  • Correct the cause of excessive fuel pressure
  • Replace faulty mixture-related sensors
  • Reset learned values and update ECM software if the manufacturer calls for it

Questions and answers

What does P02D4 mean?

The ECM could not lower the fuel delivery of the cylinder 5 injector any further because its learned correction reached the minimum limit. The injector itself or a rich condition in that cylinder is the usual cause.

Can I drive with code P02D4?

Briefly and carefully, yes, but have it checked soon. A rich mixture raises fuel use and can lead to misfires and catalytic converter damage.

Will clearing the code fix it?

No. If the underlying fault remains, the learned value will hit the limit again and the code will return. Find the injector, wiring or fuel pressure problem first.

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.