Ignition

P03FE — Ignition L Control Circuit Low

Severity: medium Drive with care, to a shop

What P03FE means

The engine control module monitors the control signal for the ignition 'L' circuit, which drives an ignition coil or ignition module. P03FE sets when the voltage in that circuit stays lower than expected, for example from an open circuit, a short to ground or a failing driver. Normally the ECM sends a timed pulse, the coil builds energy and fires the spark plug at the right moment.

Symptoms

  • Check Engine light on
  • Misfire or rough idle
  • Reduced power and sluggish acceleration
  • Hard starting
  • Worse fuel economy
  • Hesitation under load

Possible causes

  1. Failed ignition coil in the L circuit
  2. Damaged wiring or corroded coil connector
  3. Control wire shorted to ground
  4. Worn spark plugs or damaged secondary ignition parts
  5. Faulty ignition control module
  6. Rarely, a failed ECM

How to diagnose

  1. Scan all codes and freeze frame data, and look for misfire codes (P030x)
  2. Inspect the coil connector and harness for corrosion, chafing or heat damage
  3. Check power, ground and control signal at the coil connector using the wiring diagram
  4. Test the control wire to the ECM for opens and shorts to ground
  5. Swap the coil with a neighboring one and see if the code follows
  6. Inspect spark plugs and gap
  7. Test the ignition module if it is a separate part
  8. Suspect the ECM only after everything else checks out

Common fixes

  • Replace the faulty ignition coil
  • Repair the wiring or replace the connector
  • Replace spark plugs and any damaged boots or wires
  • Replace the ignition control module
  • Repair or replace the ECM after confirmed diagnosis

Questions and answers

What does P03FE mean?

It means the ECM detected a low signal in the Ignition L control circuit. The usual culprits are the ignition coil or its wiring.

Can I drive with P03FE?

A short trip to a shop is usually fine, but the engine may misfire. That can harm the catalytic converter, so do not put off the repair.

How do I fix P03FE?

Start with the coil connector and wiring, then test the coil and spark plugs. If those are good, the ignition module or ECM needs diagnosis.

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.