Faulty glow plug with internal short to earth; Damaged, chafed or corroded wiring between the glow plug control unit and the cylinder 5 glow plug shorted to earth; Loose, corroded or water-damaged connector or terminal at the cylinder 5 glow plug or control module; Faulty glow plug control module or output driver for cylinder 5; Low supply voltage or poor earth caused by a weak battery or bad connection; Fault in the engine control unit output stage or software issue (model-specific).

P067C

Cylinder 5 Glow Plug Control Circuit Low.

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
7C: FaultThe specific fault in that area

What it means

P067C is the generic code for a low signal in the glow plug control circuit for cylinder 5. The control unit drives or monitors the glow plug circuit for that cylinder and saw a voltage lower than expected, which usually points to a short to earth, a wiring fault or a failed driver or glow plug. The code only applies to diesel engines with at least five cylinders, and the exact circuit layout depends on the engine.

Symptoms

Glow plug or engine management warning light on
Hard or extended cranking on cold starts
White smoke or rough running after a cold start
Misfire or uneven idle when cold
Slightly higher emissions or poorer cold drivability
Often no noticeable symptoms when the engine is warm

Possible causes

Faulty glow plug with internal short to earthlikely
Damaged, chafed or corroded wiring between the glow plug control unit and the cylinder 5 glow plug shorted to earthlikely
Loose, corroded or water-damaged connector or terminal at the cylinder 5 glow plug or control modulepossible
Faulty glow plug control module or output driver for cylinder 5possible
Low supply voltage or poor earth caused by a weak battery or bad connectionpossible
Fault in the engine control unit output stage or software issue (model-specific)rare

How to diagnose

Read all stored and pending codes and note freeze frame data, including coolant temperature and battery voltage, and check for other glow plug codes
Visually inspect the cylinder 5 glow plug wiring, connector and terminal for chafing, heat damage, corrosion and moisture
Check battery condition and charging voltage, and inspect the main supply and earth connections to the glow plug system
Disconnect the cylinder 5 glow plug and measure its resistance, comparing it with the specification for that engine
Check the control wire from the module to the plug for a short to earth using a multimeter, with the connector unplugged
Use a scan tool to activate the glow plug circuit and watch the live data or current draw for cylinder 5 compared with the other cylinders
Check the glow plug control module supply, earth and output signal, following the manufacturer's wiring diagram for the engine
Clear the code and retest to see if it returns once the repair is made

How to fix

Replace the cylinder 5 glow plug if it is shorted or out of specification, taking care not to snap it when removing it
Repair or replace damaged wiring and fit new connectors or terminals where there is corrosion or heat damage
Clean and secure the connector and earth points, and restore proper contact and sealing
Replace the glow plug control module or repair the engine control unit if testing shows a failed output driver
Replace a weak battery and repair any charging or supply voltage problems

Can I keep driving?

Low severity

The car can normally be driven, but cold starting may be harder and emissions may be slightly worse. Book it in soon, especially before cold weather, and avoid repeated long cranking attempts.

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