P0676
Cylinder 6 Glow Plug Circuit
If your vehicle's onboard computer has flagged the diagnostic trouble code P0676, it refers to a detected anomaly regarding "Cylinder 6 Glow Plug Circuit". This systemic engine fault needs a targeted check before symptoms expand.
Driver's Summary
When your OBD2 scanner shows P0676, the engine control module has flagged an issue specifically related to cylinder 6 glow plug circuit. The most common signs are hard start condition, white smoke unburned diesel smell. No immediate danger, but addressing this soon will prevent potential emissions test failures and minor system degradation.
Symptoms
Hard start condition, white smoke unburned diesel smell
Common Causes
- Failed cylinder 6 glow plug
- Melted wiring harness
- Loose connection at the glow plug
- Faulty relay
How to Fix
- 1 Replace the glow plug
- 2 Splicing new wire for the harness
- 3 Secure electrical connections
- 4 Replace relay module
Technical Explanation
P0676 is stored after the control module confirms the fault over multiple ignition cycles, ruling out transient electrical noise as the cause. The PCM distinguishes between electrical faults (circuit codes) and performance faults (rationality codes) by comparing the sensor's reported value against what other sensors would predict under the same engine operating conditions. Once confirmed, the code is stored as a permanent DTC and the MIL is activated. The freeze frame snapshot — recording RPM, load, coolant temperature, and fuel trim at fault detection — is also saved and is critical for accurate diagnosis.
Is It Safe to Drive?
Low-severity fault — you'll notice hard start condition, white smoke unburned diesel smell but the vehicle remains drivable. The risk of ignoring it long-term is a failed smog test and the possibility that a minor $80 fix becomes more complex over time.
Mechanic's Pro Tip
Before replacing any component on P0676, spend 5 minutes inspecting the wiring harness and connector first — corrosion, chafed insulation, and backed-out pins cause the majority of these faults and cost nothing to fix. Use a multimeter to measure voltage drop across the connector pins under load; anything above 0.1V indicates excessive resistance that will cause intermittent failures even after replacing the sensor.
Glow plug: $80 - $250