P037D code meaning
Glow Plug Sense Circuit
Powertrain system Generic code P03xx codes Check engine light
What P037D means
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.
P037D 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 P037D
- 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
Common causes of P037D
- Most likelySense wire open or high resistance, connector corroded
- PossibleGlow relay or glow plug control module giving an implausible feedback
- PossibleFuse or fusible link of the glow plug supply blown
- Less likelyEngine module internal
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 P037D 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. |
| 7D | The exact fault in that area. |
What to do next
- Note P037D 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 P037D
What does P037D mean?
P037D means "Glow Plug Sense Circuit". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P037D?
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 P037D fail an emissions test?
Yes, it can. P037D 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 P037D to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P037D 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.