Fuel and air

P02FB — Cold Start Fuel Injector Control Circuit Open

Severity: medium Drive with care, to a shop

What P02FB means

Some engines use a dedicated cold start injector that adds extra fuel when a cold engine is cranked. The engine control module monitors the electrical circuit that drives this injector. P02FB sets when the circuit is open or out of range, so fuel delivery during a cold start is not controlled as intended.

Symptoms

  • Hard starting when the engine is cold
  • Rough idle right after a cold start
  • Check Engine light on
  • Increased fuel consumption
  • Hesitation while the engine warms up

Possible causes

  1. Open, chafed or corroded wiring in the cold start injector circuit
  2. Loose or damaged injector connector
  3. Failed cold start injector with an open coil
  4. Faulty engine coolant temperature sensor giving wrong data
  5. Failed ECM injector driver (uncommon)

How to diagnose

  1. Scan all codes and review freeze frame data for the conditions when it set
  2. Inspect the injector harness and connector for damage, chafing and corrosion
  3. Check the connector fit and terminal condition
  4. Measure injector coil resistance and compare to the manufacturer spec
  5. Check power and ground at the injector and test the wire to the ECM for continuity
  6. Check coolant temperature sensor readings with a scan tool
  7. Verify the ECM control signal with a test light or scope
  8. Clear the code and see if it returns after a cold start

Common fixes

  • Repair damaged wiring, replace the connector or clean the terminals
  • Replace the failed cold start injector
  • Replace the coolant temperature sensor if its readings are wrong
  • Repair, reflash or replace the ECM if everything else checks out

Questions and answers

Can I drive with a P02FB code?

Usually yes, but expect hard cold starts and a rough idle. Get it fixed soon, especially before winter.

What most often causes P02FB?

Wiring or connector problems at the cold start injector are the most common, followed by the injector itself. A bad ECM is much less likely.

Will clearing the code fix it?

Clearing only turns the light off temporarily. If the fault remains, the code will return on the next cold start.

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.