P0676

Code

Generic P — Powertrain

Cylinder 6 Glow Plug Circuit/Open

Brand: Generic

Type: P — Powertrain

Views: UK: 30 EN: 50 RU: 30

AI status

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Page language: EN

Causes

Open or broken wiring between ECM/relay and glow plug #6
Failed glow plug (open or burned out)
Corroded/loose connector or terminal at the glow plug
Blown fuse or faulty glow-plug relay
High-resistance connection or poor ground
Faulty ECM/driver output for the glow-plug circuit

Symptoms

Check Engine Light (MIL) illuminated with stored P0676
Hard starting or extended cranking, especially when cold
White smoke or poor cold-start combustion from affected cylinder
Rough idle or misfire during warm-up
Glow-plug indicator or preheat lamp behavior abnormal on some vehicles

What to check

Read and record freeze frame and live data; note battery voltage and glow-plug command status
Visual inspection of glow plug #6, connector, wiring harness, relay, fuses, and ground points
Measure resistance of glow plug #6 to engine ground with it removed
Back-probe connector for voltage while commanding glow ON and check for continuity to ECM/relay
Check for corrosion, damaged pins, or loose terminals at connectors
Swap glow plug #6 with another cylinder (if identical) and re-scan to see if code follows

Signal parameters

Glow plug resistance: typically low (fractions of an ohm up to a few ohms); an open is very high/infinite
Supply voltage at glow-plug terminal when commanded ON: near battery voltage (~12 V) (may be pulsed/duty-controlled on some systems)
Typical current draw per glow plug: several amps (varies by engine; commonly ~5–20 A)
No voltage (0 V) or open-circuit reading indicates an open wiring/connector or failed plug
Driver output duty cycle or on-time visible in scan tool live data when ECM commands glow

Diagnostic algorithm

Retrieve stored codes, freeze-frame and live data. Confirm P0676 is current and note battery voltage and glow command state.
Perform a careful visual inspection of glow plug #6, its connector, wiring harness, and nearby grounds for damage, corrosion, or loose terminals.
With ignition OFF, disconnect the glow plug connector and measure resistance of glow plug #6 from terminal to engine ground. Compare to specification; an open/infinite reading indicates a failed glow plug.
Reconnect and back-probe the connector. With key ON and command active (use scan tool to command glow), measure voltage at the terminal. If voltage is present but plug is open, replace the glow plug.
If no voltage at the connector when commanded, trace wiring back to the relay/fuse and ECM: check fuse continuity, test the glow-plug relay operation, and verify wiring continuity to the ECM driver pin.
Check for short to ground or short to battery in the circuit using insulation resistance/continuity tests. Repair any damaged wiring or connectors.
Swap glow plug #6 with a confirmed-good plug from another cylinder and clear codes. If the code moves to the other cylinder number, the plug was faulty; if it remains P0676, suspect wiring/driver.
If wiring and relay test good but no driver output from the ECM, inspect ECM grounds and related power supplies. Consult wiring diagrams and manufacturer procedures before replacing the ECM.
After repairs, clear codes and perform multiple cold-start cycles or road tests to verify the fault does not return.

Likely causes

Glow plug #6 is open (infinite resistance) or internally failed
Wiring harness damage or pin pushed out at connector to cylinder 6
Connector corroded or contaminated causing open circuit
Failed glow-plug relay or blown fuse supplying the bank/circuit
ECM output transistor for cylinder 6 is open or not commanding current

Fault status

⚠️ Status

DTC P0676 — Cylinder 6 Glow Plug Circuit/Open. MIL illuminated; ECM has detected an open or abnormal condition in glow-plug circuit for cylinder 6 and stored freeze-frame data.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5–2 hours