Skip the auto shop - Our mechanics make house calls

P0380 OBD-II Trouble Code: Glow Plug/Heater Circuit “A” Malfunction

check engine light

P0380 code definition

The P0380 trouble code notes an issue with the glow plug heater circuit A.

What the P0380 code means

The P0380 code is a standard OBD-II trouble code suggesting an issue within the glow plug heater circuit. When the powertrain control module (PCM) detects a variation in the voltage from the “A” area of the glow plug heater circuit that is more than a 10 percent variation from the expected output, the P0380 code will be detected. This code is associated with numerous other glow plug trouble codes.

What causes the P0380 code?

Many things can trigger the P0380 code. Some of the more common issues include:

  • Malfunctioning glow plug or relay
  • Faulty glow plug timer
  • Faulty glow plug module
  • Blown fuse in the circuit
  • Faulty wiring and electrical connectors, such as corroded connectors or open wiring

What are the symptoms of the P0380 code?

When the P0380 trouble code is triggered, it will likely be accompanied by the check engine soon Warning Light, as well as the globe plug indicator Warning Light. The vehicle also may have a difficult time starting, may be excessively noisy during start-up, and may produce white exhaust smoke.

How does a mechanic diagnose the P0380 code?

The P0380 code will be diagnosed using a standard OBD-II trouble code scanner. A professional mechanic will use the scanner to observe the freeze frame data. Using the freeze frame data, the mechanic can learn more about the P0380 code, and search for additional codes (it is common for the P0380 code to be accompanied by other glow plug trouble codes). The technician will then reset the trouble codes and restart the vehicle, to see if the codes return. If the codes do not return, it is assumed that they are intermittent and that the glow plug heater circuit is in working order.

If the P0380 code returns, the mechanic should inspect the wires, connectors, and fuses around the glow plug heater circuit. Any loose or open wires, corroded or damaged connectors, or blown fuses should be replaced. Following replacement, the trouble codes should once again be reset, and the vehicle restarted, to see if the issue has been resolved. If it has not, the mechanic will remove the glow plug in the A area and test it, as well as the relay. If needed, the components will be replaced, and all remaining trouble codes should be addressed as well.

Common mistakes when diagnosing the P0380 code

The most common mistake when diagnosing the P0380 code comes from a failure to properly follow the OBD-II trouble code diagnosis protocol. Mechanics should always follow the proper protocol in order, which includes addressing numerous trouble codes in the order in which they appear.

Failure to follow the proper protocol can also result in the glow plug or relay being replaced when the wires, connectors, or fuses were the actual issue.

How serious is the P0380 code?

A detected P0380 code is unlikely to render a vehicle as unable to operate, but it will keep the engine from running properly.

What repairs can fix the P0380 code?

The most common repairs for the P0380 trouble code include:

  • Replacement of a glow plug or glow plug relay
  • Replacement of heater circuit wires, connectors, and fuses
  • Replacement of glow plug timer or module

Additional comments for consideration regarding the P0380 code

While blown fuses in the glow plug heater circuit are commonly associated with the P0380 code, they are usually the result of a deeper issue. If a blown fuse is detected, it should be replaced, but it shouldn’t be assumed to be the only issue or the cause of the P0380 trouble code.

Need help with a P0380 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.


Post a question and get free advice from our certified mechanics.


More related articles

How to Buy Fuel Treatments
Adding a fuel additive to your gas tank when you fill up is one way to clean vital engine parts of deposits, improve the performance of your engine,...
Insurance Requirements for Car Registration in Kentucky
The Kentucky Transportation Cabinet requires that all drivers in Kentucky carry liability automotive insurance, or “financial responsibility” in order to operate a vehicle legally and maintain vehicle...
Veteran and Military Driver Laws and Benefits in New Mexico
The state of New Mexico offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch...

Related questions

Q: I have 05 audi a 6 Quattro 4.2. I sprayed the engine off one afternoon. Now I'm getting primary/ secondary circuit malfunction sho

This is a common problem with the Audi models. Generally one of the advantages to having coil packs instead of a distributor is that they are a little more water resistant, however this is a known issue with Audi in...

Q: Car randomly becomes harder to start

It could possibly be a fuel pressure issue. When you turn the key, you should hear a brief buzz from the back of the car. That should be the fuel pump priming the fuel system with pressure to make the...

Q: Crank but not start, There is spark and fuel spray in injector, I change the PCM and distributor box but still the same no start

If you are getting spark and fuel to the engine then the only thing left to check is the compression in the engine. Have a compression test done to see if the timing belt may have jumped timing. You should...