U019C code meaning
Lost Communication With Glow Plug Control Module 2
Network system Generic code U01xx codes Check engine light
What U019C means
U019C points to a second glow plug control module, needed where a diesel has more preheating channels than one unit drives, for example one module per cylinder bank. No manufacturer documents U019C publicly; it is absent from GM's diesel tables and from the NHTSA bulletin index. The partner code U0106 for module 1 shows the logic: GM's 2015 engine diagnostics table fails it when no GPCM frame has arrived for more than 0.25 s during a 10 s test and rates it Type B. CARB requires glow plugs to be checked for correct current and response to commands, which presumes a live link to the module. The plugs on the affected side may stay cold, giving hard cold starts, rough running and white smoke while warming up; an MIL is to be expected. U049D is invalid data.
U019C at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U019C
- Hard starting when cold
- White smoke and rough idle until warm
- Preheat lamp behaves oddly, MIL on
Common causes of U019C
- Most likelyGlow plug module 2 without supply, ground or ignition feed
- PossibleWater or corrosion in the module connector near the engine
- PossibleBus line to module 2 chafed or connector loose
- Less likelyGlow plug control module 2 faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Glow plug module 2CAN bus
What each part of U019C means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 9C | The exact fault in that area. |
What to do next
- Note U019C and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U019C
What does U019C mean?
U019C means "Lost Communication With Glow Plug Control Module 2". U019C points to a second glow plug control module, needed where a diesel has more preheating channels than one unit drives, for example one module per cylinder bank. It is a generic code, so it means the same on every make.
Is it safe to drive with U019C?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will U019C fail an emissions test?
Yes, it can. U019C is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U019C to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will U019C clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.