P037E code meaning
Glow Plug Sense Circuit Low
Powertrain system Generic code P03xx codes Check engine light
What P037E means
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.
P037E at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P037E
- Check engine light on
- Possibly hard starting or knocking when cold
- Further glow plug codes
Common causes of P037E
- Most 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
- Less likelyWeak battery or vehicle voltage at the edge of the enable range
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Glow plug supplyGlow plug wiringEngine control module
What each part of P037E means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 3 | Area: ignition system or misfire. |
| 7E | The exact fault in that area. |
What to do next
- Note P037E and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P037E
What does P037E mean?
P037E means "Glow Plug Sense Circuit Low". P037E means the voltage read back from the glow plug supply is too low. It is a generic code, so it means the same on every make.
Is it safe to drive with P037E?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P037E fail an emissions test?
Yes, it can. P037E is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P037E to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P037E clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.