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P0381 is a diagnostic trouble code (DTC) for "Glow Plug/Heater Indicator Circuit Malfunction". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
The P0381 code represents a problem with the glow plug or heater indicator circuit. In some vehicles, this code is sometimes also referred to as the “wait to start lamp control circuit.” The code is often accompanied by other glow plug circuit codes, such as P0380, which indicates a malfunction in heater circuit A, or P0382, which specifies heater circuit B.
P0381 is the OBD-II generic code for a glow plug/heater indicator circuit malfunction. The glow plug system, found in diesel vehicles, helps to provide heat in order to start the engine in cold temperatures. The ECM (Engine Control Module) monitors coolant temperature and glow plug voltage, facilitating the plugs heating before and while cranking the engine.
This code will be detected if the glow plugs are commanded off, and the voltage feedback is above 2 volts, or if they are commanded on and the feedback is not between 5 and 6.2 volts. Causes of this condition may include:
Symptoms of P0381 may include an illuminated Check Engine light, hard start or failure to start, a glow plug indicator lamp which stays on or remains illuminated too long, excessive white exhaust smoke upon startup, excessive noise upon startup, and/or a lit malfunction indicator.
While the glow plug heater circuit is simpler than many vehicle systems, certain procedures still must be followed to ascertain the source of the problem:
Sometimes the timer or relay are replaced without testing the connectors, wiring, and glow plugs. This can result in a continuation of the problem and exaggerated diagnostic and repair costs.
A glow plug heater circuit malfunction can cause the vehicle to start with difficulty, or not to start at all. This could be a dangerous situation when traveling in cold weather because it could leave you stranded in a cold vehicle.
Glow plug heater indicator circuit problems may be fixed by one of the following, depending upon the source of the malfunction:
As with any diagnostic trouble code, the stored codes should be recorded and addressed in the order the events occurred. If the codes are cleared from the vehicle and fail to return, this could indicate an intermittent condition, which can be challenging and time-consuming to diagnose. Occasionally an entire fuse bank or PCM may need to be replaced, but these are rare as causes of a P0381 code.
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