Fuel and air

P02F6 — Cylinder 9 Injector Circuit Range/Performance Fault

Severity: medium Drive with care, to a shop

What P02F6 means

The engine control module (ECM) constantly monitors the cylinder 9 injector control circuit and compares its behavior with what it expects. P02F6 is stored when the signal or feedback falls outside the acceptable range, or the injector does not perform as commanded. The cause can be electrical (wiring, connector, ECM driver) or mechanical (a sticking or clogged injector). The code applies to engines with nine or more cylinders, such as V10 and V12 designs.

Symptoms

  • Check Engine light on
  • Rough idle or misfire
  • Reduced engine power
  • Poor fuel economy
  • Hesitation under load
  • Raw fuel smell from the exhaust

Possible causes

  1. Faulty, clogged or sticking cylinder 9 injector
  2. Corroded, loose or damaged injector connector
  3. Open or short circuit (to ground or power) in the injector wiring
  4. Failed injector driver inside the ECM (uncommon)
  5. Low fuel pressure or fuel supply problem
  6. Intake air leak skewing the air-fuel mixture

How to diagnose

  1. Scan all codes and freeze frame data, and look for related injector or misfire codes
  2. Review short-term and long-term fuel trims and compare cylinder balance
  3. Inspect the cylinder 9 injector connector and harness for corrosion, chafing and poor contact
  4. Measure injector coil resistance and compare with specification and neighboring injectors
  5. Check for power and the control pulse at the connector with a multimeter or scope
  6. Test fuel rail pressure
  7. Look for intake air leaks and exhaust leaks ahead of the oxygen sensors
  8. Swap the injector with another cylinder and see whether the fault follows it

Common fixes

  • Replace the faulty cylinder 9 injector
  • Repair or replace damaged wiring and connectors
  • Clean or service the injector if contamination is the cause
  • Correct the air leak or fuel pressure problem
  • Repair or replace the ECM (injector driver) only after ruling out everything else

Questions and answers

What does P02F6 mean?

It is a generic code meaning the ECM sees the cylinder 9 injector circuit operating outside its expected range. The injector, its wiring and its connector all need to be checked.

Can I drive with code P02F6?

Only briefly and carefully, to a shop. Misfires and extra fuel in the exhaust can damage the catalytic converter, so do not put off the repair.

How do I tell a bad injector from a wiring problem?

Measure the injector coil resistance and check the control signal at the connector. You can also swap injectors between cylinders: if the fault moves, the injector is bad.

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.