P037F code meaning
Glow Plug Sense Circuit High
Powertrain system Generic code P03xx codes Check engine light
What P037F means
P037F means the voltage read back from the glow plug supply is too high. GM's 2016/2018 diesels set it when the feedback lies above a threshold derived from the run/crank relay voltage, with a feedback above 5.0 V – for example voltage is reported although the plugs are not energised, or the sense line is shorted to positive. The code needs 40 of 80 samples at 50 ms, about 2 of 4 s, only with the engine running, and turns on the check engine light after two trips; GM classes the cause as internal to the module. If there is a real short to positive or a stuck relay or output stage, the plugs can stay energised permanently, overheating them and draining the battery – then also check the single plug codes P0671 ff and P066x. CARB requires glow plug circuits to be monitored for correct current and voltage drop.
P037F 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 P037F
- Check engine light on
- Glow plugs possibly energised permanently (flat battery, plug damage)
- Glow plug light implausible
Common causes of P037F
- Most likelySense wire chafed against positive or bridged in the connector
- PossibleGlow relay sticking or output stage shorted (supply stays on)
- PossibleMeasuring circuit in the engine module
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 moduleGlow plug relay
What each part of P037F 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. |
| 7F | The exact fault in that area. |
What to do next
- Note P037F 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 P037F
What does P037F mean?
P037F means "Glow Plug Sense Circuit High". P037F means the voltage read back from the glow plug supply is too high. It is a generic code, so it means the same on every make.
Is it safe to drive with P037F?
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 P037F fail an emissions test?
Yes, it can. P037F 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 P037F to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P037F 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.