Faulty or shorted cylinder 10 glow plug (internal short or damaged element); Wiring to the cylinder 10 glow plug chafed or shorted to ground; Corroded, loose or damaged connector or terminal at the glow plug or control module; Moisture or oil contamination in the glow plug connector or harness; Faulty glow plug control module or output driver; Engine control unit fault or outdated software, where the manufacturer has documented this.

P069C

Cylinder 10 Glow Plug Control Circuit Low.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
6: AreaComputer and output circuits
9C: FaultThe specific fault in that area

What it means

P069C means the engine control unit or glow plug control module has detected a low voltage condition on the control circuit for the cylinder 10 glow plug. The circuit is reading lower than expected, which points to a short to ground, a high-resistance fault or a failed driver. Cylinder numbering and how the glow plug circuits are arranged depend on the engine, so check the manufacturer's layout.

Symptoms

Hard starting or extended cranking in cold weather
White smoke or rough running for the first few minutes after a cold start
Glow plug or engine warning light on
Slightly higher cold-start emissions or diesel knock
Other glow plug circuit codes stored alongside it

Possible causes

Faulty or shorted cylinder 10 glow plug (internal short or damaged element)likely
Wiring to the cylinder 10 glow plug chafed or shorted to groundlikely
Corroded, loose or damaged connector or terminal at the glow plug or control modulepossible
Moisture or oil contamination in the glow plug connector or harnesspossible
Faulty glow plug control module or output driverpossible
Engine control unit fault or outdated software, where the manufacturer has documented thisrare

How to diagnose

Read all stored and pending codes and note the freeze frame data, including coolant temperature and battery voltage
Check for other glow plug codes. A pattern across several cylinders suggests the module or its supply rather than a single plug
Visually inspect the glow plug wiring and connector for cylinder 10 for chafing, heat damage, corrosion, oil or water
Check the battery condition and the glow plug supply fuse and relay, as the manufacturer specifies
Measure the glow plug resistance and compare it with the manufacturer's specification, with the plug disconnected
Test the control wire for a short to ground and for continuity back to the module, with the harness disconnected and the system safe
Use a scan tool to command the glow plug output, if supported, and check the module's response and the current draw
Check for manufacturer service bulletins or software updates relating to the glow plug module for that engine

How to fix

Replace the cylinder 10 glow plug if its resistance or element is out of specification, following the manufacturer's torque and removal procedure
Repair or replace the damaged wiring section that is shorted to ground
Clean or replace corroded connectors and terminals and make sure they are sealed properly
Replace the glow plug control module if the output driver has failed and the wiring and plug have tested good
Apply a manufacturer software update only if an outdated calibration is a known cause for that engine

Can I keep driving?

Medium severity

The car can usually be driven short term, but cold starting and emissions may suffer. Get it checked soon, as a short to ground can stress the control module and blow fuses.

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