Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
The car's computer thinks the heater for one of the engine's cylinders is getting too much power.
The P066B code indicates that the Engine Control Module (ECM) has detected a high voltage condition in the glow plug control circuit for cylinder 1.
Glow plugs are used in diesel engines to help start the engine by heating the air in the cylinder. The control circuit for these plugs is monitored by the ECM. If the voltage in this circuit is higher than expected, the ECM will trigger the P066B code.
• Difficulty starting the engine
• Rough idling
• Check Engine Light illuminated
• Faulty glow plug
• Damaged wiring or connectors
• Faulty glow plug control module
ECM: Engine Control Module
OBD-II: On-Board Diagnostics, Second Generation
• Use an OBD-II scanner to confirm the code.
• Inspect the glow plug and its wiring for damage.
• Test the glow plug control module for proper operation.
• Replace the faulty glow plug.
• Repair or replace damaged wiring or connectors.
• Replace the glow plug control module if necessary.
• OBD-II scanner
• Multimeter
• Socket set
$100 - $300
Moderate
• Ford F-250
• Chevrolet Silverado 2500
• Dodge Ram 2500
• Regularly inspect glow plug connections.
• Ensure the glow plug system is maintained during service.
• Use high-quality parts for replacements.
Engine Performance
• Have the vehicle inspected by a professional.
• Avoid prolonged cranking of the engine.
• Monitor the engine's starting performance.
Check with the vehicle manufacturer for warranty coverage on glow plug systems.
Glow plug circuit issues have been common in diesel engines, especially in cold climates where starting is more challenging.
Moderate – While the vehicle may still operate, starting issues can worsen and lead to more significant engine problems.
Always ensure vehicle repairs are conducted safely and in accordance with local regulations.
• Engine off and cool
• Battery fully charged
The glow plug is located in the cylinder head of the engine.
Q: Can I drive with a P066B code?
A: Driving is possible, but it may lead to starting issues and should be addressed soon.
Q: How do glow plugs work?
A: Glow plugs heat the air in diesel engine cylinders to help start the engine.
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