Ignition

P031E — Ignition Control Circuit (Circuit D) Fault or Misfire Condition

Severity: medium Drive with care, to a shop

What P031E means

P031E does not have a clearly defined standard meaning in the generic OBD-II list, so its exact definition depends on the manufacturer. Some references link it to ignition control circuit "D" (typically the fourth coil or a module channel) or to a misfire condition. The PCM triggers the spark through a control signal to the coil or module and watches both circuit feedback and crankshaft speed variation. When the signal or response is out of range, it stores the code and turns on the check engine light. Confirm the exact definition for your vehicle in the service information.

Symptoms

  • Check engine light on or flashing
  • Rough idle
  • Misfires and vibration
  • Hesitation or stumbling on acceleration
  • Worse fuel economy
  • Loss of power
  • Hard starting

Possible causes

  1. Failed ignition coil or ignition module
  2. Open, corroded or shorted wiring or connector in the ignition control circuit
  3. Worn spark plugs overloading the coil
  4. Crankshaft position or timing sensor problem
  5. Poor ground or low supply voltage at the coils
  6. Internal PCM fault (rare)

How to diagnose

  1. Scan all codes and freeze frame data, and look for related misfire codes (P0300-P0312) or coil circuit codes (P0350-P0362).
  2. Look up the P031E definition for your make and model in service information.
  3. Inspect coil and PCM connectors and harnesses for corrosion, chafing, heat damage or moisture.
  4. Check spark plug condition and gap, and replace worn plugs as a set.
  5. Swap the suspect coil with one from another cylinder and see whether the fault follows it.
  6. Test coil power and ground with a multimeter, and the PCM control signal with a scope if available.
  7. Check the crankshaft position sensor and its signal.
  8. Consider PCM testing or replacement only after everything else is ruled out.

Common fixes

  • Replace the faulty ignition coil or module
  • Replace spark plugs
  • Repair or replace damaged wiring and connectors
  • Replace the crankshaft sensor if confirmed bad
  • Reprogram or replace the PCM as a last resort

Questions and answers

What does P031E mean?

It has no firmly standardized definition. It is most often linked to an ignition control circuit or misfire condition, but you need the manufacturer's information for the exact meaning on your vehicle.

Can I drive with P031E?

Only briefly, and only if the engine runs smoothly. If the check engine light flashes or the engine shakes, stop, since misfires can damage the catalytic converter.

Where should I start fixing P031E?

Scan for other codes, then inspect the spark plugs, coils and connectors. Swapping a coil to another cylinder is a quick way to see if the coil is the cause.

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.