What Does P0380 Mean?
The ECM has detected a malfunction in the glow plug or intake air heater circuit A on a diesel engine. The glow plug system preheats the combustion chambers to aid cold starting, and this code indicates the circuit responsible for powering the glow plugs has a fault. The driver will likely notice hard starting in cold weather, extended cranking, white smoke on startup, and the glow plug indicator light may not illuminate or may stay on longer than normal.
Common Causes
35%
One or more burned-out glow plugs creating an open circuit or excessive current draw
25%
Failed glow plug relay or glow plug control module
20%
Corroded or loose glow plug bus bar connections or power feed wiring
10%
Blown glow plug fuse or fusible link
10%
Wiring fault between ECM/GPCM and the glow plug circuit (open or short)
Diagnostic Steps
1
Measure battery voltage first (must be >12.4V). Then check for battery voltage at the glow plug bus bar during a glow cycle (key on, engine off). No voltage indicates a relay, fuse, or wiring fault upstream.
2
Test each glow plug individually by measuring resistance from the terminal to ground. Specification is typically 0.5-2.0 ohms. Replace any plug showing open circuit (OL) or significantly out-of-spec resistance.
3
Check the glow plug relay or GPCM by commanding it on with a scan tool bidirectional test. Verify the relay clicks and voltage passes through. Measure relay coil resistance (typically 70-120 ohms) and contact resistance (<0.5 ohms).
4
Inspect the glow plug power supply circuit: check the fusible link, main fuse, and all high-current connections from the battery to the glow plug bus bar. Measure voltage drop under load (should be <0.5V total from battery to plugs).
5
Using a clamp-on ammeter, measure total glow plug circuit current draw during a glow cycle. Compare to expected draw (number of cylinders x 15-25A per plug). Significantly low current indicates open plugs; high current indicates shorted plugs.
Estimated Repair Cost
$100 - $700
Parts + labor, varies by vehicle and location
The ECM has detected a malfunction in the glow plug or intake air heater circuit A on a diesel engine. The glow plug system preheats the combustion chambers to aid cold starting, and this code indicates the circuit responsible for powering the glow plugs has a fault. The driver will likely notice ha...
The most common cause of P0380 (Glow Plug/Heater Circuit A Malfunction More details...) is: One or more burned-out glow plugs creating an open circuit or excessive current draw
Typical repair costs for P0380 range from $100 to $700, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle is safe to drive once started and warmed up. The primary risk is inability to start in cold conditions, which could leave you stranded. In warm climates, the impact is minimal. Schedule repair before cold weather; not an immediate safety concern for warm-weather driving.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0380 to identify the root cause.
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Quick Info
Category
Powertrain
System
Diesel Glow Plug / Cold Start System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
