P0380: Glow Plug/Heater Circuit "A"

Is your scanner showing P0380?
No worries. We'll show you what it means and how to deal with it.

Presented by

Randy Worner

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P0380: Glow Plug/Heater Circuit "A"

OVERVIEW

Severity

Medium

DIY Difficulty Level

Intermediate

Repair Cost

$100-$400

Can I Still Drive?

Yes

What Does The P0380 Code Mean?

The glow plug operates when starting a cold diesel engine (the powertrain control module PCM uses the coolant temperature when the ignition is switched on to determine this).

The glow plug heats up red hot for a short period of time to increase the cylinder temperature allowing the diesel fuel to ignite more easily. If there is an open in the glow plug or circuit this DTC will set.

On some diesel engines, the PCM will operate the glow plugs for a period of time after the engine is running to reduce white smoke and engine noises.

Basically, the P0380 code means that the PCM has detected a fault in the glow plug/heater circuit “A”.

Note: This DTC is very similar to P0382 which that code refers to circuit “B”. If you have multiple DTC codes, fix them in the order they appear.

What Are The Symptoms Of The P0380 Code?

Symptoms of a P0380 trouble code may include:

Malfunction Indicator Lamp (MIL) illumination
Glow plug / Wait To Start indicator stays illuminated longer than normal (may be on solid)
Hard to start condition especially in colder weather

What Are The Potential Causes Of The P0380 Code?

Potential causes for this DTC may include:

Fault in glow plug wiring (open, short to ground, etc.)
Glow plug faulty
Open fuse
Faulty glow plug relay
Faulty glow plug module

How Can You Fix The P0380 Code?

If you have a GM truck or really any vehicle for that matter, check for known issues such as TSBs (technical service bulletins) that pertain to this code.
Check associated fuses, replace if blown. Test glow plug relay if possible.
Visually inspect the glow plugs, wiring, and connectors for corrosion, wiring pins bent/loose, loose screws/nuts on wiring connections, burnt appearance. Repair as necessary.
Check harness connectors for resistance using a digital volt ohm meter (DVOM). Compare to manufacturer specifications.
Disconnect glow plug wires, measure resistance using DVOM, compare to spec.
Use a DVOM to verify that the glow plug wiring connector is getting power and ground.
If replacing a glow plug, be sure to start it in the threads by hand first, just like you would a spark plug.
If you really want to test the glow plug, you could always remove them, apply 12V to the terminal and ground the body for a 2-3 seconds. If it glows red hot it’s good, if it’s a dull red or not red, it’s no good.
If you have access to an advanced scan tool, there may be functions you could use on it that pertain to the glow plug wiring circuit.

Other Glow Plug related DTCs: P0381, P0382, P0383, P0384, P0670, P0671, P0672, P0673, P0674, P0675, P0676, P0677, P0678, P0679, P0680, P0681, P0682, P0683, P0684.