P031D

What it means

P031D means the engine control unit has detected an open circuit on the control signal line to ignition driver or coil D. The control unit monitors the ignition control signal and has found it missing, or it did not see the expected electrical response. Which cylinder 'D' refers to depends on the engine and manufacturer, so confirm this in the vehicle-specific data.

Symptoms

• Engine misfire, rough running or shaking at idle
• Malfunction indicator lamp on, possibly flashing under load
• Loss of power or poor acceleration
• Hard starting or extended cranking
• Increased fuel consumption
• Engine may enter a reduced-power mode

Possible causes

• Faulty ignition coil or integrated coil driver for position Dlikely
• Open circuit, chafed or broken wire in the ignition control signal wiring between the engine control unit and coil Dlikely
• Corroded, loose or damaged connector terminals at the coil or engine control unitlikely
• Missing or poor power supply or earth to the coil, causing the driver to not respond properlypossible
• Wiring harness damage from heat, oil contamination or rodent damage near the enginepossible
• Fault inside the engine control unit output driverrare

How to diagnose

1. Read all stored and pending codes and note any other ignition, misfire or circuit codes, then review the freeze frame data for engine speed, load and temperature when the fault set.
2. Check the vehicle-specific information to identify which coil or cylinder is 'D' on this engine.
3. Inspect the coil connector, harness and engine control unit connector for corrosion, bent or pushed-back pins, oil ingress, heat damage and chafing.
4. Check for misfire counts on the affected cylinder with live data and see whether the fault is constant or intermittent.
5. Swap coil D with a known good coil from another cylinder, clear the codes and see whether the fault or the misfire follows the coil.
6. With the connectors disconnected, test the control signal wire for continuity end to end and for shorts to earth or supply, following the wiring diagram.
7. Check the coil power supply and earth connections under load using a multimeter or oscilloscope, and check the control signal waveform if equipment allows.
8. Only if the wiring, supplies and coil all test good, consider testing the engine control unit output, after checking for any applicable software updates for the model.

How to fix

• Replace the faulty ignition coil or coil driver for position D, using the correct part for the engine.
• Repair or replace the damaged section of wiring in the control signal circuit, using proper soldered or crimped and sealed joints.
• Clean, repair or replace corroded or damaged connectors and terminals.
• Restore the correct power supply or earth to the coil circuit, including any faulty relay, fuse or earth point.
• Replace or repair the engine control unit only after all other causes have been ruled out and the fault is confirmed.

Can I keep driving?

Nearby codes

• P031CGenericIgnition C Control Signal Circuit High
• P031EGenericIgnition D Control Signal Circuit Low