P066C

Symptoms

• Difficulty starting a diesel engine in cold weather
• The Check Engine light comes on
• Increased starter cranking time
• White smoke from the exhaust pipe during cold start
• Unstable engine operation after starting

Causes

• Short circuit of the glow plug control wire of cylinder 2 to ground
• Damaged or broken wiring in the control circuit
• Glow Plug Control Module (GPCM) Malfunction
• Faulty glow plug cylinder 2 (internal short circuit)
• Oxidation or damage to control circuit connectors

How to Fix

1. Read error codes with an OBD-II scanner, write down all active codes
2. Inspect the wiring and connectors of the cylinder 2 glow plug and GPCM
3. Measure the voltage in the glow plug control circuit of cylinder 2
4. Check the resistance of the glow plug of cylinder 2 (normal: 0.5–2 Ohm)
5. Check the circuit for short circuit to ground
6. If the wiring is working properly - diagnostics and replacement of the GPCM or spark plug

Related codes

Error P066C by Vehicle Brand