Engine

P037F — Glow Plug Sense Circuit High

Severity: medium Safe to drive

What P037F means

The engine control unit or a dedicated glow plug control module monitors voltage or current in the glow plug circuit. P037F sets when that signal reads higher than expected. Typical causes are a bad glow plug, damaged wiring or connectors, or a faulty control module.

Symptoms

  • Check Engine light or glow plug indicator on
  • Hard starting when the engine is cold
  • Rough idle after a cold start
  • White smoke at cold start
  • Weak performance during warm-up
  • Poor fuel economy

Possible causes

  1. Faulty glow plug or an open circuit in one plug
  2. Damaged wiring or high resistance in the harness
  3. Corroded or loose connectors and terminals
  4. Faulty glow plug control module
  5. Internal ECM/PCM fault (unlikely)

How to diagnose

  1. Scan for codes and freeze frame data, and look for other glow plug or power supply codes
  2. Inspect wiring, connectors and the control module ground for damage and corrosion
  3. Check battery and charging system voltage
  4. Measure each glow plug's resistance with a multimeter and compare it with the engine's specification
  5. Test the control module's supply and output signals using the wiring diagram
  6. Check continuity and resistance of the wires between the module and the plugs
  7. If all is normal, test the ECM and update its software if needed

Common fixes

  • Repair wiring and clean or replace connectors
  • Replace faulty glow plugs, ideally as a full set
  • Replace the glow plug control module
  • Reflash or replace the ECM/PCM if the fault is confirmed

Questions and answers

What does P037F mean?

It means a high signal in the glow plug sense circuit of a diesel engine. The usual culprits are the glow plugs, wiring or the glow plug control module.

Can I drive with code P037F?

Usually yes, but cold starting may get worse, especially in winter. It's best to have it fixed soon.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.