P0380 Code: Glow Plug/Heater Circuit A Malfunction
🟠 Moderate severity · drivable
Drivable, but expect harder starts in cold weather until the glow plug circuit is fixed.
What P0380 means
The glow plug circuit (circuit A) isn't working right. Glow plugs heat the cylinders before a cold start on diesel engines, so a bad circuit means harder starting when it's cold.
Symptoms
- Check engine light is on
- Hard starting in cold weather
- White smoke at cold start
- Rough idle right after starting
Common causes
- most common: Faulty glow plug
- common: Faulty glow plug relay or control module
- less common: Damaged wiring or connector
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Test and replace the faulty glow plug | Yes | $20–100 |
| Replace the glow plug relay or control module | Yes | $50–200 |
| Repair damaged glow plug wiring | Mechanic | $50–150 |
Frequently asked questions
Can I drive with a P0380 code?
Yes, but the engine will be harder to start in cold weather until the circuit is fixed.
What is the most common cause of P0380?
A worn or failed glow plug, which is a common part on diesel engines.
How much does it cost to fix a P0380?
Typically $20–$100 per glow plug, plus a little labor if a shop does the work.
Related codes
P0381
P0381 Code: Glow Plug Indicator Control Circuit Open
P0382P0382 Code: Glow Plug/Heater Circuit B Malfunction
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.