P0383
Glow Plug Control Module 1 Control Circuit Low
Glow plug system (diesel)
Generic OBD-II
High
What it means
P0383 sets when the engine computer sees low voltage (a short to ground or open) on the control circuit for the diesel glow plug control module. Glow plugs pre-heat the cylinders for cold starting, so the main symptoms are hard cold starts, rough cold running, and white smoke — not a warm-engine no-start. It usually traces to the module, a fuse, or the control wiring.
High
Can I keep driving? The engine runs normally once warm; the main effect is hard or delayed cold starting and rough cold running until the glow plug circuit is fixed.
Common symptoms
What you'll notice
- Check-engine light (and often the glow-plug warning light) on
- Hard or delayed cold starting
- Rough idle and misfire when the engine is cold
- White exhaust smoke on cold start-up
Common causes
Most likely first
- Faulty glow plug control module / relayLikely
- Low-side control circuit shorted to ground or openCommon
- Damaged, corroded, or high-resistance wiring or a blown fuse in the glow-plug circuitCommon
- Failed engine control module (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and confirm the glow plug control module low-side circuit is at fault.
- Check the glow-plug fuse and inspect the control module connector and wiring for shorts to ground or corrosion.
- Measure the control circuit voltage from the ECM to the module.
- Test the glow plug control module's operation with a scan tool.
- Replace the control module or repair the wiring as indicated. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0383?+
Yes once the engine is running — glow plugs mainly help cold starting. Expect hard cold starts and a bit of white smoke until it's repaired.
Can I just clear P0383?+
You can, but it returns until the glow plug control circuit is fixed. It also won't restore easy cold starting on its own.
Related codes
Often seen with P0383
Read & clear P0383 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX