Faulty glow plug (internal short or high resistance) affecting the sense reading; Corroded, loose or damaged connector or terminal on the glow plug feed or sense circuit; Wiring fault such as chafed insulation causing a short to earth, or an open circuit, on the sense wire; Low battery voltage or poor power or earth supply to the glow plug controller; Faulty glow plug control module or relay; Engine control unit internal fault or outdated software, where the manufacturer lists it as a known cause.

P037E

Glow Plug Sense Circuit Low.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
3: AreaIgnition system or misfire
7E: FaultThe specific fault in that area

What it means

P037E means the control unit has seen a voltage on the glow plug sense circuit that is lower than expected. The sense circuit is how the glow plug controller or engine control unit monitors glow plug voltage or current. A low reading usually points to a short to earth, an open or high-resistance circuit, or a failed glow plug or controller. How the circuit is laid out and which glow plug it covers depends on the model and engine.

Symptoms

Glow plug warning light on, or engine management light on
Hard starting or extended cranking when cold
White smoke and rough running after a cold start
Misfire or unstable idle until the engine warms up
Higher emissions or poor cold-running performance
No noticeable symptoms when warm

Possible causes

Faulty glow plug (internal short or high resistance) affecting the sense readinglikely
Corroded, loose or damaged connector or terminal on the glow plug feed or sense circuitlikely
Wiring fault such as chafed insulation causing a short to earth, or an open circuit, on the sense wirepossible
Low battery voltage or poor power or earth supply to the glow plug controllerpossible
Faulty glow plug control module or relaypossible
Engine control unit internal fault or outdated software, where the manufacturer lists it as a known causerare

How to diagnose

Read all stored and pending codes and the freeze frame data, noting engine temperature, battery voltage and mileage when the code set. Check for other glow plug codes.
Check battery condition and charging voltage, as low supply voltage can upset glow plug monitoring.
Inspect the glow plug wiring, connectors, feed cables and fuses for corrosion, heat damage, chafing and loose terminals.
Check the glow plug controller supply and earth connections for voltage drop under load.
Measure each glow plug's resistance and compare with the manufacturer's specification, and check for shorts to earth.
With a suitable scan tool, view live glow plug data or run the glow plug activation test if the vehicle supports it, and watch the sense voltage.
Check the sense circuit for continuity and for a short to earth using the wiring diagram for that model and engine.
If everything else checks out, test the glow plug controller by following the manufacturer's procedure, and check for relevant software updates.

How to fix

Replace any glow plugs that fail resistance or short-circuit tests, using the correct type for the engine.
Repair or replace damaged wiring, connectors or terminals, and clean up any corrosion.
Restore a good power supply and earth connection to the glow plug system, and fix any battery or charging fault.
Replace the glow plug control module or relay if it is confirmed faulty.
Apply a manufacturer software update only if a known fault with the control unit calibration is confirmed.
Clear the codes and retest from a cold start to confirm the fault does not return.

Can I keep driving?

Medium severity

The car can usually be driven short-term, but cold starting may get harder and the fault could get worse. Have it checked soon, especially before cold weather or if the engine runs roughly.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.