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.
Low severity. Can I keep driving?You can keep driving, although cold starts will be harder. Avoid cranking the starter repeatedly on cold days.
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
Most 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
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It affects emissions.
What each character of P037D means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 3: Ignition and misfires
- 7D: Specific fault in that system
Frequently asked questions
Can I keep driving with code P037D?
You can keep driving, although cold starts will be harder. Avoid cranking the starter repeatedly on cold days.
What causes code P037D?
The most common causes are: 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.
Related codes
- P037EGlow Plug Sense Circuit Low
- P037FGlow Plug Sense Circuit High
- P0380Glow Plug/Heater Circuit A
- P0670Glow Plug Control Module 1 Control Circuit/Open
- P0671Cylinder 1 Glow Plug Circuit/Open
Sources
- law.cornell.edu: 13 CCR 1968.2
- gsi.ext.gm.com: 18OBDG04 Engine Diagnostics
- saabwisonline.com: p0380 0f
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.