Ignition

P031F — Ignition D Control Circuit High

Severity: medium Drive with care, to a shop

What P031F means

P031F means the engine control module detected a high signal voltage in the ignition D control circuit. This is usually the fourth coil or ignition driver channel, but which cylinder it maps to depends on the manufacturer. The module sends a control pulse that lets the coil build energy and fire the spark plug. When the circuit voltage goes outside the expected range, the module sets the code.

Symptoms

  • Check Engine light on
  • Rough idle
  • Engine misfires
  • Loss of power and weak acceleration
  • Hard starting
  • Worse fuel economy

Possible causes

  1. Failed ignition coil for channel D
  2. Control wire shorted to voltage or open circuit
  3. Corroded or damaged coil connector
  4. Faulty ignition control module or driver
  5. Faulty PCM or software error

How to diagnose

  1. Scan all codes and freeze frame data, and note any misfire codes.
  2. Find out from a wiring diagram or service manual which coil is channel D on your vehicle.
  3. Inspect the coil connector and harness for heat damage, chafing, corrosion and loose pins.
  4. Swap coil D with a known good coil and see whether the code or misfire follows it.
  5. Use a multimeter to check power, ground and the control signal at the coil connector per the diagram.
  6. Test the control wire from the coil connector to the PCM for opens and shorts to voltage.
  7. If the coil and wiring are good, test the ignition module, then the PCM, and check for software updates.

Common fixes

  • Replace the faulty ignition coil D
  • Repair the wiring or replace the damaged connector
  • Replace the ignition control module
  • Replace or reprogram the PCM once confirmed faulty

Questions and answers

What does P031F mean?

It means the PCM detected a high signal in the ignition D control circuit. The usual culprits are the coil, wiring or connector.

Can I drive with P031F?

A short trip to a shop is usually fine if the engine runs smoothly. If it misfires badly or the check engine light flashes, stop to avoid damaging the catalytic converter.

Is replacing the coil enough?

Not always. Check the wiring and connector first, because a short to voltage can damage a new coil as well.

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.