Fuel and air

P02F4 — Cylinder 7 Injector Circuit Range/Performance Fault

Severity: medium Drive with care, to a shop

What P02F4 means

P02F4 means the engine control module detected that the electrical or operating values of the cylinder 7 injector circuit are outside the expected range. The ECM normally pulses the injector open for a calculated time and monitors current and voltage in the circuit. When the response does not match what it expects, it stores the code and turns on the check engine light.

Symptoms

  • Check engine light on
  • Rough idle or engine vibration
  • Reduced power and sluggish acceleration
  • Increased fuel consumption
  • Misfire on cylinder 7
  • Hesitation or jerking under load

Possible causes

  1. Faulty cylinder 7 fuel injector
  2. Damaged or corroded wiring harness to the injector
  3. Poor connection at the injector or ECM connector
  4. ECM injector driver fault (uncommon)
  5. Fuel supply problem such as low fuel pressure
  6. Air leak causing a mixture deviation

How to diagnose

  1. Read all codes and freeze frame data, and look for related misfire codes
  2. Inspect the cylinder 7 injector connector and harness for chafing, corrosion and loose terminals
  3. Review fuel trims and compare cylinder balance with a scan tool
  4. Measure injector coil resistance and compare it with the spec for your engine
  5. Check power and ground at the connector, and verify the control pulse with a scope or noid light
  6. Test fuel rail pressure
  7. Inspect the intake for vacuum or air leaks
  8. Swap the injector with a neighboring cylinder to see if the fault follows it

Common fixes

  • Replace the faulty cylinder 7 injector
  • Repair wiring or replace damaged connectors and terminals
  • Clean a clogged injector if it is otherwise healthy
  • Fix any air leak or fuel pressure problem found
  • Repair or replace the ECM if the driver fault is confirmed (rare)

Questions and answers

Can I drive with P02F4?

Only briefly and to a repair shop. A misfiring cylinder can overheat the catalytic converter and burn extra fuel, so don't put the repair off.

What usually causes P02F4?

Most often it is the cylinder 7 injector itself or a wiring or connector problem leading to it. Check the connector and harness first, then test the injector resistance.

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.