Failed glow plug on cylinder 11 with an open heating element; Damaged, corroded or loose wiring or connector between the glow plug and the control module for cylinder 11; Corroded or loose glow plug terminal or power feed connection at the plug; Blown fuse or fusible link in the glow plug supply (if it feeds only the affected circuit, depending on model); Faulty glow plug control module output stage for that cylinder; Wiring harness chafed or broken by heat or vibration near the engine.

P0681

Cylinder 11 Glow Plug Circuit/Open.

Generic
Powertrain
Generic code
Low severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
6: AreaComputer and output circuits
81: FaultThe specific fault in that area

What it means

P0681 means the control unit has detected an open circuit in the glow plug circuit for cylinder 11, using the SAE J2012 generic definition. The glow plug control module or engine control unit monitors current or voltage in the circuit and sets the code when it sees no load, which suggests the circuit is not completing. Cylinder 11 only exists on large engines (typically V12 or similar), so this code is rare on ordinary passenger cars.

Symptoms

Hard starting or extended cranking when the engine is cold
White smoke or rough running for the first minute after a cold start
Glow plug or engine warning light on the dashboard
Misfire or uneven idle on cold start that clears when warm
Noticeably increased diesel knock on cold start

Possible causes

Failed glow plug on cylinder 11 with an open heating elementlikely
Damaged, corroded or loose wiring or connector between the glow plug and the control module for cylinder 11likely
Corroded or loose glow plug terminal or power feed connection at the plugpossible
Blown fuse or fusible link in the glow plug supply (if it feeds only the affected circuit, depending on model)possible
Faulty glow plug control module output stage for that cylinderpossible
Wiring harness chafed or broken by heat or vibration near the enginerare

How to diagnose

Read all stored and pending codes and note the freeze frame data, including coolant temperature, and check for other glow plug codes.
Check the vehicle-specific cylinder numbering to confirm which physical glow plug is cylinder 11, as this varies by engine.
Visually inspect the glow plug wiring, connector and terminal for cylinder 11 for damage, corrosion, heat damage or looseness.
Check the relevant fuses and supply connections to the glow plug system against the wiring diagram.
With the plug disconnected, measure the glow plug resistance and compare it with the specification for that engine.
Check for supply voltage and ground at the connector when the module commands the glow plugs, following the manufacturer procedure.
Use a scan tool that supports live data or output tests to see whether the module commands the circuit and reports current, if the model allows it.
If the plug and wiring test good, check the glow plug control module and its connector for faults.

How to fix

Replace the failed glow plug, using the correct specification for the engine and tightening to the stated torque.
Repair or replace damaged wiring, terminals or the connector for cylinder 11.
Clean and secure loose or corroded terminal and supply connections.
Replace the blown fuse or fusible link after finding and fixing the reason it failed.
Replace the glow plug control module if the output for that cylinder has failed and all wiring and the plug test good.

Can I keep driving?

Low severity

The car can normally be driven, as only one glow plug circuit is affected, but cold starts may be harder and rougher. Book it in soon, especially before cold weather, and avoid repeated long cranking.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.