P066F

Symptoms

• Difficulty starting a diesel engine in cold weather
• The Check Engine light comes on
• Extended warm-up time before starting
• White smoke from exhaust pipe on cold start
• Unstable engine operation at idle

Causes

• Short circuit of the glow plug control wire of cylinder 3 to power
• Open ground circuit in control circuit
• Glow Plug Control Module (GPCM) Malfunction
• Damage to control circuit wiring or connectors
• Internal ECU fault

How to Fix

1. Read error codes with an OBD-II scanner, capture a freeze frame of the data
2. Inspect the wiring and connectors of the cylinder 3 glow plug and GPCM
3. Measure the voltage in the spark plug control circuit of cylinder 3
4. Check the ground circuit for open circuit with a multimeter
5. Check signal wire for short circuit to power
6. If the wiring is working properly, diagnose and replace the GPCM or ECU

Related codes

Error P066F by Vehicle Brand