What P0382 means
P means powertrain (engine and transmission). The 0 marks a generic code defined by SAE, so the same number means the same thing across makes. The third character, 3, places it in the ignition system or misfire subsystem; the last two digits identify the specific fault.
Glow plugs heat the combustion chambers of a diesel engine to help it start from cold. A relay or glow plug control module powers them, and the engine computer monitors the circuit and the dashboard glow indicator.
The letter "B" distinguishes between two or more of the same component on one vehicle. Which physical part is "B" is set by the manufacturer, so confirm it in the service information before replacing anything.
What “Circuit” means here
"Circuit" is the broadest fault type in the standard. The module has found the diesel glow plug system circuit electrically unusable: the signal is missing, outside its electrical limits, or the module's own self-test of the circuit failed. Some vehicles set this instead of the more specific low/high codes; others set it alongside them. Either way the first suspect is the wiring and connector, then the component, and only then the module.
What you may notice
Symptoms depend on the vehicle and on how the module responds to the fault. Any of these can accompany P0382:
- Hard cold starting
- White smoke and rough running just after a cold start
- Glow plug lamp behaving oddly
Where to start diagnosing P0382
- Test each glow plug's resistance or current draw.
- Check the glow plug relay or control module and its fuse.
- Inspect the bus bar or individual wires to the plugs.
Clear the code only after recording freeze frame data: it shows the engine speed, load and temperature at the moment the fault set, which is often the best clue to reproducing it.
Live data to watch
These standard OBD2 values relate to P0382. Support varies by vehicle; a value your car does not report will simply be missing.
| Value | What to look for |
|---|---|
| Engine coolant temperature (PID 0x05) | Glow time depends on it. |
| Engine RPM (PID 0x0C) | Cranking time to start. |
Related codes
Codes from the same diesel glow plug system family. If several are stored together, the shared part — wiring, a common reference voltage, or the component itself — is the place to start.
Further reading
Frequently Asked Questions
What does P0382 mean?
P0382 is the generic SAE J2012 code for "Glow Plug/Heater Circuit "B"". In plain terms, it means the engine computer has detected a "circuit" fault on the diesel glow plug system.
Can I keep driving with P0382?
Usually drivable once warm; cold starts may be difficult.
What should I check first for P0382?
Test each glow plug's resistance or current draw.
Definition source: SAE J2012 / ISO 15031-6 generic DTC definitions. This is the generic meaning that applies across makes; a manufacturer can define a code more narrowly or add its own sub-codes, so confirm against the service information for your vehicle before replacing parts. Written by the OBDAssistant engineering team — see our editorial policy.