P037EGlow Plug Sense Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- 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.
- What you may notice
- Check engine light on
- Possibly hard starting or knocking when cold
- Further glow plug codes
- Likely causes
- LikelyHigh contact resistance in the glow plug supply (connector, ground, fusible link)
- PossibleMeasuring circuit or output stage in the engine module
- PossibleSense or supply wire shorted to ground
- RareWeak battery or vehicle voltage at the edge of the enable range
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.