Engines find it hard to start up after a cold night, and diesel engines are even worse when it comes to cold starts. Fortunately, most diesel engines have glow plugs that heat up their combustion chambers. Glow plugs play an important role in your vehicle’s engine performance, fuel efficiency, and emission control during cold starts.
If the powertrain control module (PCM) detects a problem in the glow plug/heater circuit “A”, its diagnostics will log a P0380 code.
What Does the P0380 Code Mean?
The Diagnostic Trouble Code (DTC) P0380 indicates “Glow Plug/Heater Circuit “A” Malfunction.”
When you start your vehicle, the PCM checks parameters, such as the coolant temperature, to see if the diesel engine is hot enough to run properly. If it detects that the engine is cold, the computer will activate the glow plugs. These plugs produce intense heat that raises the cylinder temperature, making it easier to burn the diesel fuel.
Depending on your vehicle’s diesel engine design, the glow plugs can keep running for a short time after the engine gets hot enough. This extended operation helps the engine burn the air-fuel mixture more completely, which reduces white smoke and noise.
The PCM regularly checks the performance of the glow plugs. If the computer doesn’t get the right response from the glow plug, it will set the powertrain code P0380.
Note: The definition of code P0380 may differ according to the vehicle manufacturer. Check the appropriate repair manual or repair database for the exact code definition.
What are the Possible Causes of the P0380 Code?
- Bad glow plug relay
- Problems with the glow plug control unit
- Faulty glow plugs
- Issues with the connectors and wires in the glow plug wiring harness
- Open fuse
- An issue with the PCM, such as software in need of an update
What are the Common Symptoms of the P0380 Code?
- Check engine light illuminates
- Difficulty in starting the engine, especially during cold starts
How to Diagnose the P0380 Code
If you’re not confident about conducting diagnostic tests on your vehicle’s glow plugs, it’s a good idea to bring it to a certified mechanic. Otherwise, you may go ahead and diagnose the issue yourself. To help you get started, here are some videos that may give you an idea of what the process might involve:
How to Fix the P0380 Code
Attempting to fix a P0380 code may become a frustrating task if you don’t have the right tools and know-how to test the glow plugs, the control unit, its relay, and its wiring harness. In most cases, it’s best to leave the job to professionals.
For DIYers with advanced technical knowledge and hands-on experience who prefer to test and replace their vehicle’s glow plugs and associated parts on their own, it will be helpful to rely on the appropriate repair manual or refer to an online repair database.
Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic.