P0380 moderate

Glow Plug/Heater Circuit A

The P0380 code means the vehicle's onboard diagnostic system has detected: Glow Plug/Heater Circuit A. This is a moderate severity code.

My Garage →
Keep driving?
Yes, but fix soon
DIY difficulty
moderate
Estimated cost
$100 - $500 (parts and labor)
Recommended Tool
ANCEL AD310 OBD-II Scanner

Best-selling code reader on Amazon. Reads and clears check engine codes on any 1996+ vehicle. Under $30.

Check Price on Amazon

Affiliate link -- we earn a commission at no extra cost to you.

Every Tech Needs This
AstroAI Digital Multimeter

Essential for diagnosing sensor codes, checking voltage, and testing circuits. Under $15 and pays for itself on the first job.

Check Price on Amazon

Affiliate link -- we earn a commission at no extra cost to you.

Common Symptoms

  • Check Engine Light on
  • Hard starting in cold weather
  • White smoke on cold start
  • Rough idle until engine warms up

Probable Causes (Ranked by Likelihood)

  • One or more faulty glow plugs Very High
  • Faulty glow plug relay or control module High
  • Damaged wiring in glow plug circuit Moderate
  • PCM/glow plug module communication fault Low

Step-by-Step Diagnostic Procedure

  1. Test each glow plug individually with a clamp-on ammeter. Each should draw 15-25 amps.

  2. Measure glow plug resistance. Typical: 0.5-2 ohms. Infinite ohms = open (failed) plug.

  3. Check glow plug relay or controller for proper operation. Should activate with key on.

  4. Inspect wiring bus bar connecting glow plugs for corrosion or damage.

Frequently Asked Questions

What do glow plugs do?

Glow plugs heat the combustion chamber in diesel engines to help ignite fuel during cold starts. They operate for a few seconds before and during cranking.

Can I drive with bad glow plugs?

Yes, once the engine is running it does not need glow plugs. However, cold starts will be very difficult, and you may see white smoke until the engine warms up.

How many glow plugs does a diesel have?

One per cylinder. A 4-cylinder diesel has 4, a V6 has 6, and a V8 has 8 glow plugs.

Sources

This page is built from documented references. Verify against your own service info before repair work.

P0380 on Diesel, EV & Equipment

The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:

Bobcat serious Glow Plug / Heater Circuit A Malfunction Duramax moderate Glow Plug / Heater Circuit 'A' Malfunction Kubota moderate Glow Plug / Heater Circuit 'A' Malfunction PACCAR minor Glow Plug Control Circuit Power Stroke moderate Glow Plug/Heater Circuit A Yanmar serious Glow Plug / Heater Circuit A Malfunction

Explore More

Search codes Vehicle-specific fixes Guides By make

Was this helpful?

Share carcodefinder.com with a friend who needs to decode their check engine light.

Browse by symptom → Read repair guides → Fixes by vehicle →