Error Code P0380 is defined as Glow Plug/Heater Circuit “A” Malfunction. Meaning, there’s a problem with the glow plug heater circuit of the vehicle, causing the vehicle to have difficulty in starting and exhausting smoke.

This code is a generic trouble code, meaning it applies to all vehicles made since 1996 up to present. Specifications on the definition, troubleshooting and repair of course, vary from one make and/or model to another.

For GM vehicles for example, the description is slightly different, which says: Glow Plug Performance Conditions.

This code is commonly found on Chevrolet, GMC, Volkswagen and Ford diesel-equipped vehicles. But they can be possibly found in other makes as well, such as Citroen, Saab, etc.

Definition

The Glow Plug works when starting a cold diesel engine. The PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) uses the coolant temperature when the ignition is switched on to determine the cold diesel engine. The Glow Plug then heats up (glowing) for a short period of time to increase the temperature of the cylinder and allow the diesel fuel to ignite more easily. If there is open in the circuit or in the glow plug, then the code P0380 is set.

Basically, the code refers to the fault in the glow plug/heater circuit “A”. Another Error Code which is very similar to this code is the P0382, which refers to circuit “B”. For vehicles with multiple codes, the best way to fix them is by the order they appear.

To reduce engine noise and smoke, some diesel engines operate the glow plugs for a period of time after the engine is running.

Common Symptoms

As with other error codes, the most common symptom of Error Code P0380 is the activation of the Check Engine light. Other symptoms include:

  • Hard starting, especially on cold weather
  • Glow plug/Wait To Start indicator remains illuminated longer than usual (may be on solid)
  • Excessively noisy during start-up
  • White smoke coming out from the exhaust

Possible Causes

There are many things that can cause or trigger this error code, some of the most common causes include:

  • Defective glow plug or relay
  • Defective glow plug timer
  • Defective glow plug module
  • Open fuse
  • Blown fuse in the circuit
  • Corroded connectors, open wiring, or other faulty wiring or electrical connector issues

How to Check

As with other trouble codes, technicians diagnose this trouble code using the standard OBD-II trouble code scanner. They take note of the vehicle’s freeze frame data and use that information about the code.

They search for any additional codes present, as this code can be accompanied by other glow plug trouble codes.

Then, the technician will reset the trouble codes and restart the vehicle to see if the codes come back. If the codes DO NOT come back, that means the problem is intermittent, and the glow plug heater circuit is still working properly.

If the code comes back however, the technicians will then proceed to check the connectors, wire and fuses around the glow plug heater circuit. Any open wires, loose wires, damaged or corroded connectors, and blown fuses must be replaced.

After the replacement, the trouble codes must be once again reset and the vehicle must be restarted to see whether the problem is resolved or not. If the problem is still not resolved, then the technician will proceed on removing the glow plug A from its area and test it, along with the relay. If deemed defective, then it must be replaced. All remaining trouble codes present must be addressed accordingly as well.

How to Fix

Repairs for this error code are pretty simple and straightforward, some of the most common fixes are:

  • Replacement of the faulty glow plug or glow plug relay
  • Replacement of p=glow plug timer or glow plug module
  • Repair or replacement of faulty or damaged connectors, wirings and fuses

This code is unlikely to cause the vehicle un-operational, but it can definitely make the engine run poorly.

Also, while blown fuses in the glow plug heater circuit is usually associated with the error code P0380, it can also be a result of a deeper issue. Blown fuses should be replaced as soon as possible. However, you should not always assume that it is the only cause of the trouble code.