P0676: Cylinder 6 Glow Plug Circuit

What it means

An electrical fault is present in the glow plug circuit for cylinder 6. The glow plug control module cannot drive this plug correctly — open circuit, short, or out-of-range resistance — so cylinder 6 is not pre-heated. On a cold start this causes hard starting, white smoke, and a misfire-like rough run until the engine warms. Causes: a failed glow plug, a broken supply lead to that plug, corrosion at the plug connector, or a faulty module output for cylinder 6.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

The glow plug in cylinder 6 preheats that cylinder, while the glow plug control module controls the electrical supply to the plug. P0676 sets when the module detects an electrical problem in the cylinder 6 glow plug circuit, such as an open, short, or resistance outside the manufacturer’s specification. This code points to cylinder 6’s circuit specifically.

Common causes

Most likely first.

1. Failed cylinder 6 glow plug
2. Open or shorted wiring to the plug
3. Corroded or loose connector
4. Glow plug control module output fault

Symptoms

• Glow plug warning light on (often orange coil symbol)
• Hard cold start or no start in cold weather
• White smoke from exhaust during warm-up

How to diagnose it

1. Record freeze-frame data and check for other cylinder-specific glow-plug codes to see whether the problem is isolated to cylinder 6.
2. Locate cylinder 6 from the vehicle’s service information and inspect its glow plug connector, lead, and nearby harness for corrosion, looseness, or damage.
3. Isolate the circuit as specified by the manufacturer and measure the cylinder 6 glow plug against the manufacturer’s specification.
4. Check the cylinder 6 wiring for opens and shorts from the plug connector toward the module.
5. If the plug and wiring pass, test the glow plug module’s cylinder 6 output using the prescribed scan-tool or electrical procedure.
6. After correcting the fault, clear the code and confirm it remains absent after a cold-start cycle.

Common fixes

• Clean and secure the cylinder 6 connector.
• Repair damaged wiring or terminals in the cylinder 6 branch.
• Replace the cylinder 6 glow plug if it fails the specified test.
• Repair or replace the module’s cylinder 6 output if the plug and wiring are good.

Can I keep driving?

If the engine runs normally once warm, limited driving may be possible, but cold starting can be difficult and the engine may run roughly or emit white smoke while warming. Avoid repeated cranking and address it promptly if symptoms persist after warm-up.