What Does P069B Mean?
The PCM has detected a high voltage condition on the glow plug control circuit for cylinder 9. This indicates the control circuit has lost its ground path or there is a short to battery voltage, preventing proper glow plug activation. The cylinder 9 glow plug may not heat at all, causing cold start difficulties, white smoke, and a misfire on that cylinder during warm-up on diesel engines.
Common Causes
30%
Open circuit in the glow plug wiring (broken wire or disconnected connector at cylinder 9)
30%
Failed glow plug with open heating element (infinite resistance)
20%
Failed glow plug control module unable to complete the ground circuit for cylinder 9
15%
Corroded or backed-out terminal at the glow plug connector or control module
5%
Short to battery voltage in the control wire from an adjacent harness wire
Diagnostic Steps
1
Measure the resistance of the cylinder 9 glow plug from its terminal to engine ground; an open-loop (OL/infinite) reading means the glow plug element has burned open and needs replacement.
2
Verify continuity of the control wire from the glow plug control module connector to the cylinder 9 glow plug connector; should read near 0 ohms.
3
Inspect the glow plug connector for backed-out terminals, corrosion, or heat damage; these connectors operate in extreme heat environments.
4
With the glow plug disconnected, check the control module output; it should provide battery voltage during the glow cycle. If not, the module driver for cylinder 9 may have failed.
5
Check for voltage on the control wire with the glow plug and module disconnected; any voltage present indicates a short to B+ from an adjacent wire.
Estimated Repair Cost
$50 - $400
Parts + labor, varies by vehicle and location
The PCM has detected a high voltage condition on the glow plug control circuit for cylinder 9. This indicates the control circuit has lost its ground path or there is a short to battery voltage, preventing proper glow plug activation. The cylinder 9 glow plug may not heat at all, causing cold start ...
The most common cause of P069B (Cylinder 9 Glow Plug Control Circuit High) is: Open circuit in the glow plug wiring (broken wire or disconnected connector at cylinder 9)
Typical repair costs for P069B range from $50 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A single non-functional glow plug on a large diesel engine will make cold starts more difficult and cause rough running during warm-up. The vehicle is generally safe to drive once warmed up. In very cold weather, the engine may fail to start if additional glow plugs have marginal performance.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P069B to identify the root cause.
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Quick Info
Category
Powertrain
System
Diesel Glow Plug / Cold Start System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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