Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means there's a problem with the little heater in the engine that helps it start when it's cold. It's not working properly for cylinder number 8.
The P0678 code indicates an issue with the glow plug circuit in cylinder 8, which is essential for starting a diesel engine in cold conditions.
The glow plug circuit for cylinder 8 is either open or has a malfunction, meaning that the electrical current required to heat the glow plug is not reaching it. This can result in poor starting performance, especially in cold weather.
• Hard starting
• Rough idling
• Increased exhaust smoke
• Faulty glow plug
• Damaged glow plug wiring
• Faulty glow plug control module
Glow Plug: A device used to heat the air in a diesel engine to help it start.
Circuit: A path for electrical current to flow.
• Check the glow plug for cylinder 8 for continuity.
• Inspect the wiring and connectors for damage or corrosion.
• 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.
• Multimeter
• Socket set
• Wiring repair kit
$100 - $300
Moderate
• Ford F-Series
• Chevrolet Silverado
• Dodge Ram
• Regularly inspect glow plug wiring.
• Replace glow plugs at recommended intervals.
• Keep the engine free of moisture and corrosion.
Sensor Issue
• Have the vehicle inspected by a professional if you experience hard starting.
• Do not ignore the check engine light as it may lead to further issues.
Glow plugs may be covered under the vehicle's powertrain warranty.
Glow plug issues are common in diesel engines, particularly in older models or those frequently exposed to cold weather.
Moderate – While the vehicle may still run, it's important to address this issue to ensure reliable starting and performance.
Ignoring this issue can lead to increased emissions and potential engine damage.
• Engine cold start
• Ambient temperature below freezing
The glow plug for cylinder 8 is located in the engine cylinder head, typically on the driver's side of the engine.
Q: What happens if I ignore this code?
A: Ignoring this code can lead to hard starting, especially in cold weather, and may cause further engine damage.
Q: Can I drive with a P0678 code?
A: You can drive, but it's recommended to fix the issue soon to avoid starting problems and increased emissions.
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