Fault code P037E – glow plug sense circuit low

Fault code P037E is called “Glow Plug Sense Circuit Low” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P037E

OBD-II fault code P037E is a generic code defined as “low signal in glow plug sensor circuit”. It is set when the Powertrain Control Module (PCM) detects a general fault or failure. Which has occurred in the glow plug sensor circuit on a diesel engine.

Fault code P037E – glow plug sense circuit low

Glow plugs are used on diesel engines to provide an intense heat source. Which is necessary to provide better combustion of the fuel-air mixture when the engine is cold or the temperature is below the minimum threshold.

At low ambient temperatures, it is very difficult to ignite the diesel mixture because it may not be compressed enough to initiate combustion. Diesel engines use electrically heated glow plugs to eliminate these problems. To create a heat source in the precombustion chamber of each cylinder, to ignite the fuel-air mixture at the peak of compression.

Regardless of the ambient temperature, the glow plug control circuit will not be activated. If the engine coolant temperature exceeds a predetermined minimum threshold.

This is necessary both to extend the service life of the glow plugs and to prevent premature detonation of the fuel-air mixture.

Glow plugs are critical components of a diesel engine. Because if they fail, there is a high probability that a cold engine will not start or will start with great difficulty.

Consequently, if the glow plug sensor circuit fails, the PCM or other control module will set code P037E. A special light on the control panel may also turn on.

Symptoms of vehicle malfunctions

The main signal that an error P037E has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. The “Check engine” control lamp on the control panel will light up (the code will be recorded in the memory as a malfunction).
  2. The glow plug start standby light is on longer than usual (may be permanently on).
  3. The engine may crank but not start (especially in cold weather).
  4. Possible white smoke from the exhaust pipe due to insufficient heating of fuel before combustion.
  5. Increased engine noise.
  6. Reduced power output of the engine.
  7. Increased fuel consumption.

Depending on the symptoms, the error P037E may be minor or serious. However, the problem should not be ignored, as the occurrence of this error may cause problems with the engine.

Factors that can cause this error code

The error code P037E can mean that one or more of the following problems have occurred:

  • One or more glow plugs are defective.
  • Faulty glow plug wiring.
  • Blown fuse or fusible link.
  • Faulty glow plug relay.
  • Faulty ignition switch is faulty.
  • Glow plug control module.
  • Glow plug timer defective.
  • The engine coolant temperature sensor may have failed.
  • Sometimes the cause is a defective PCM module.

How to fix or reset OBD-2 code P037E

Some suggested steps for troubleshooting and fix the error code P037E:

  1. Read all stored data and error codes with a standard OBD-II scan tool.
  2. Clear the error codes from the computer memory and recheck the system to see if error P037E appears again.
  3. If the error code disappears, then the problem is intermittent and there is nothing wrong with the glow plug circuit.
  4. If the code appears again, visually inspect the electrical wires and connectors as well as the fuses.
  5. Then check the glow plugs as well as the control relay.
  6. Replace defective components if necessary.

Diagnose and repair of problems

The best way to diagnose error P037E is to start with the Technical Service Bulletins (TSB), perhaps your problem is known and described in them. Then you should check the appropriate fuses, replace them if they are blown. Next, you should test the glow plug relays.

Visually inspect the glow plugs, wiring, and connectors for corrosion, bent, and loose wire contacts. Look for loose screws or nuts on the wiring connections. If necessary all defects should be repaired.

Check the connectors of the wiring harness for resistance using a digital voltmeter and compare with the manufacturer’s specifications. Do the same with the wires going to the glow plugs.

To check the glow plug itself, you must remove it, apply 12 V voltage to it, and ground the body for 2-3 seconds. If the glow plug is red hot, it is working, if it is dull red or not red at all, it must be replaced.

On which vehicles does this problem occur most frequently

Fault code P037E can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Chevrolet
  • Dodge (RAM)
  • Ford
  • GMC
  • Mazda
  • Opel (Astra, Meriva)
  • Subaru (Forester, Outback)
  • Volkswagen

Fault code P037E can sometimes be found with other errors. The most common are the following: P037D, P037F.


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