P031C

Symptoms

• Misfires in group C cylinders
• Unstable idle, vibration
• Loss of engine power
• Increased fuel consumption
• Check Engine Light Is On, Possibly Flashing

Causes

• Short circuit in the ignition coil control circuit C to +12V
• Group C ignition coil malfunction
• Damage to wiring or coil connector
• Malfunction of the ignition control module
• ECU malfunction (rare)

How to Fix

1. Read error codes, determine which cylinders are in group C
2. Inspect the connector and wiring of ignition coil C for damage.
3. Measure the resistance of the primary winding of the coil (standard: 0.5–2 Ohm)
4. Check the control circuit voltage with the ignition on
5. Move coil C to another group and check if the error moves
6. Replace the faulty ignition coil

Related codes

Error P031C by Vehicle Brand