P066A

Symptoms

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

Causes

• Short circuit of the glow plug control wire of cylinder 1 to ground
• Damaged or broken wiring between GPCM and ECU
• Glow Plug Control Module (GPCM) Malfunction
• Faulty glow plug of cylinder 1 (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 and saved codes
2. Visually inspect the wiring and connectors of the cylinder 1 glow plug and GPCM
3. Measure the voltage in the glow plug control circuit of cylinder 1
4. Check the resistance of the glow plug of cylinder 1 (normal: 0.5–2 Ohm)
5. Check control circuit for short to ground
6. If the wiring is in good condition - diagnostics and replacement of the GPCM module or ECU

Related codes

Error P066A by Vehicle Brand