What Does P069C Mean?
The PCM has detected a low voltage condition on the glow plug control circuit for cylinder 10 in a diesel engine. This is specific to large-displacement diesel engines (V10, V12, or inline 10+ configurations). A shorted glow plug or wiring fault is pulling the control circuit voltage below specification. The driver may experience hard cold starts and a cylinder 10 misfire during warm-up.
Common Causes
35%
Failed glow plug on cylinder 10 with internal short to ground
25%
Short to ground in the wiring between glow plug control module and cylinder 10 glow plug
20%
Failed glow plug control module output driver for cylinder 10
15%
Corroded connector or terminal at the glow plug causing low-resistance leakage
5%
Glow plug tip broken off inside the cylinder allowing combustion pressure to damage the element
Diagnostic Steps
1
Measure the resistance of the cylinder 10 glow plug from its terminal to engine ground; typical good readings are 0.5-2.0 ohms. Near-zero resistance confirms an internal short.
2
Disconnect the glow plug and measure resistance from the control wire to chassis ground; readings below 5 ohms indicate a harness short to ground.
3
Compare cylinder 10 glow plug resistance to the remaining glow plugs; all should be within specification and within 0.2 ohms of each other.
4
Inspect the glow plug connector for oil contamination, carbon buildup, or heat damage that could create a conductive path to ground.
5
If the glow plug and wiring test good, check the glow plug control module output using an ammeter; excessive current draw on the cylinder 10 circuit points to a module fault.
Estimated Repair Cost
$50 - $450
Parts + labor, varies by vehicle and location
The PCM has detected a low voltage condition on the glow plug control circuit for cylinder 10 in a diesel engine. This is specific to large-displacement diesel engines (V10, V12, or inline 10+ configurations). A shorted glow plug or wiring fault is pulling the control circuit voltage below specifica...
The most common cause of P069C (Cylinder 10 Glow Plug Control Circuit Low) is: Failed glow plug on cylinder 10 with internal short to ground
Typical repair costs for P069C range from $50 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive once the engine is running and warmed up. Cold start performance will be degraded, especially in temperatures below 40°F (4°C). A shorted glow plug can draw excessive current from the control module, potentially damaging the module and affecting other cylinders.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P069C to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Diesel Glow Plug / Cold Start System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
