What it means
A control module has lost communication with the glow plug control module. On applicable diesel vehicles, glow plug operation may be affected, particularly during cold starts.
At a glance
- Affects emissions; the car can fail an emissions test
How it works
On applicable diesel vehicles, the glow plug control module switches and monitors the glow plugs that help warm the combustion chambers for starting. It communicates its status to other modules over the vehicle network. U0106 sets when a reporting module stops receiving expected messages from the glow plug control module.
Common causes
Most likely first.
- Loss of module power or ground
- Open, shorted, or damaged communication wiring or connector
- Module or gateway fault
Symptoms
- Glow plug warning or message
- Hard starting when cold
- Communication faults in other modules
How to diagnose it
- Scan all modules for U0106 and related codes, and save freeze-frame data including engine temperature and starting conditions.
- Check for a glow plug warning or message and note whether cold starting is difficult while warm starting remains normal.
- Inspect the glow plug control module connector and nearby wiring for corrosion, heat damage, looseness, or chafing.
- Check the module's power and ground circuits and relevant fuse supply against the manufacturer's specification.
- Test the communication wiring to the module for opens, shorts, or poor connections using the vehicle wiring information.
- If its power, ground, and network circuits are sound, use vehicle-specific diagnostics to assess the module and glow plug system before replacing parts.
Common fixes
- Clean or secure a loose or corroded glow plug control module connector.
- Repair damaged wiring or a poor module ground.
- Restore the module's power supply and correct the cause of any failed fuse.
- Repair a network or gateway fault if testing identifies one.
- Replace or program the glow plug control module only after its circuits and the glow plug system have been checked.
Can I keep driving?
If the diesel starts and runs normally, you can usually drive cautiously, but allow for harder cold starts and avoid repeated starting attempts that drain the battery. If it will not start reliably or runs abnormally, arrange diagnosis before depending on it in cold conditions.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.