Powertrain, generic · Ignition system or misfire

P037D Glow Plug Sense Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

To check the glow plugs, the engine module reads back the voltage or current of the glow plug supply through a sense circuit – CARB requires glow plug circuits to be monitored for correct current and voltage drop, and from model year 2010 the failure of a single plug to be detected. In the J2012 scheme P037D is the general code for this sense circuit, P037E and P037F its low and high counterparts. None of the manufacturer documents available to us uses P037D: GM's 2016/2018 diesels use only P037E/P037F, Ford 2023 its own glow plug codes (P0671 ff, P064C) and Saab reports the feedback of its glow plug control module as P0380/P0382. The description therefore follows CARB and the GM sister codes. Typically glow plug monitoring is inactive; glowing itself can work normally.

Likely causes

Sense wire open or high resistance, connector corroded
Glow relay or glow plug control module giving an implausible feedback
Fuse or fusible link of the glow plug supply blown
Engine module internal

Symptoms

  • Check engine light or glow plug light on
  • Possibly poor cold start if the cause also affects the glow plug supply
  • Further glow plug codes stored

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–500
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

glow plug supplyglow plug wiringengine control module

Related codes

P037EP037FP0380P0670P0671

References: law.cornell.edu, gsi.ext.gm.com, saabwisonline.com.