P037E means the voltage read back from the glow plug supply is too low. GM's 2016/2018 diesels, whose glow plug output stages sit in the engine module, compare the feedback with the battery voltage while glowing: if it is lower by more than a calibrated, current-dependent threshold – excessive voltage drop or a short to ground of the sense line – a sample counts as faulty, and 60 of 120 samples in a 50 ms grid set the code, roughly 3 of 6 s. The check only runs with the engine running (afterglow), not while cranking, and is suspended if a single plug or the supply already has an electrical fault. GM classes the cause as internal to the module (measuring circuit) and turns on the check engine light after two trips. There is no limp mode; glow plug monitoring is restricted.
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 on
- Possibly hard starting or knocking when cold
- Further glow plug codes
Most likely causes
- High contact resistance in the glow plug supply (connector, ground, fusible link)
- Measuring circuit or output stage in the engine module
- Sense or supply wire shorted to ground
- Weak battery or vehicle voltage at the edge of the enable range
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 P037E means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 3: Ignition and misfires
- 7E: Specific fault in that system
Frequently asked questions
Can I keep driving with code P037E?
You can keep driving, although cold starts will be harder. Avoid cranking the starter repeatedly on cold days.
What causes code P037E?
The most common causes are: high contact resistance in the glow plug supply (connector, ground, fusible link); measuring circuit or output stage in the engine module; sense or supply wire shorted to ground.
Related codes
- P037DGlow Plug Sense Circuit
- P037FGlow Plug Sense Circuit High
- P0671Cylinder 1 Glow Plug Circuit/Open
- P0670Glow Plug Control Module 1 Control Circuit/Open
- P052FGlow Plug Control Module 1 System Voltage
Sources
- gsi.ext.gm.com: 18OBDG04 Engine Diagnostics
- gsi.ext.gm.com: 16OBDG04 Engine Diagnostics
- law.cornell.edu: 13 CCR 1968.2
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.