Failed glow plug on cylinder 11 (open heating element); Damaged or corroded electrical connector at the cylinder 11 glow plug; Broken or chafed wire in the glow plug harness; Faulty glow plug control module (GPCM) or relay; Poor ground connection for the glow plug circuit; Internal ECM driver fault (rare)

DTC codes / P06xx · Computer and output circuits / P0681

P0681Cylinder 11 Glow Plug Circuit

Q: What does code P0681 mean?

Cylinder 11 Glow Plug Circuit. P0681 indicates that the engine control module (ECM) has detected an open circuit or excessive resistance in the glow plug circuit for cylinder 11, which is typically found on diesel engines with high cylinder counts. The ECM monitors the glow plug circuit for expected current flow during the glow phase and sets this code when the current is below the expected threshold or the circuit is open.

P0681 indicates that the engine control module (ECM) has detected an open circuit or excessive resistance in the glow plug circuit for cylinder 11, which is typically found on diesel engines with high cylinder counts. The ECM monitors the glow plug circuit for expected current flow during the glow phase and sets this code when the current is below the expected threshold or the circuit is open.

SystemPowertrain

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaComputer and output circuits

Symptoms you may notice

Illumination of the check engine light or glow plug warning light
Hard starting or rough idle when the engine is cold
Excessive white smoke from the exhaust after a cold start
Noticeable misfire or engine stumble during warm-up
Often no symptoms besides the warning light, especially in mild climates

Common causes, most likely first

Failed glow plug on cylinder 11 (open heating element)
Damaged or corroded electrical connector at the cylinder 11 glow plug
Broken or chafed wire in the glow plug harness
Faulty glow plug control module (GPCM) or relay
Poor ground connection for the glow plug circuit
Internal ECM driver fault (rare)

How to diagnose and fix it

Inspect the glow plug connector and wiring for damage or corrosion
Measure the resistance of the cylinder 11 glow plug and compare to specification
Check for power and ground at the glow plug connector during the glow phase
Test the glow plug control module output and wiring continuity
Replace the faulty glow plug if resistance is out of range
Repair or replace damaged harness or connector as needed
Clear the code and verify the repair with a cold-start test

Glow plug circuit diagnostics for cylinder 11

Cylinder 11 is typically found on large diesel engines such as V12 or inline-6 configurations, so confirm the engine layout before ordering parts.
A glow plug that tests good cold can still fail when hot, so resistance checks should be done at room temperature and compared across all cylinders.
The glow plug control module often fails in ways that affect multiple cylinders, but a single-cylinder code like P0681 usually points to that specific plug or its wiring.
Corrosion inside the glow plug boot is a common cause that is easily overlooked during visual inspection.
This code does not always mean the glow plug is bad; a loose connection or faulty module can set the same code.

Can I keep driving with P0681?

You can generally continue driving with this code, but cold starting may be difficult and prolonged driving with a faulty glow plug can lead to excessive smoke and carbon buildup. Avoid heavy loads or high speeds until the issue is repaired, and address it before winter if you live in a cold climate.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.