P037F
Glow Plug Sense Circuit High
Diesel glow plug / cold start
Generic OBD-II
High
What it means
P037F is a diesel code meaning the glow plug sense circuit is reading a higher voltage than expected. Glow plugs preheat the combustion chambers to help a cold diesel start, so a fault here mainly shows up as hard cold starting, rough cold running, and white smoke. The engine generally runs normally once warm, but the circuit should still be repaired.
High
Can I keep driving? The engine usually runs once warm, but expect hard cold starts, rough cold running, and possibly white smoke until it's fixed.
Common symptoms
What you'll notice
- Check-engine (or glow plug) light on
- Hard starting when the engine is cold
- Rough running or hesitation until warmed up
- White exhaust smoke on a cold start
Common causes
Most likely first
- Faulty glow plug or glow plug sense circuitLikely
- Open or short-to-voltage in the sense circuit wiringCommon
- Poor or corroded connection at the glow plug or control moduleCommon
- Faulty glow plug control moduleLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and confirm the fault is the glow plug sense circuit reading high.
- Inspect the glow plug harness and connectors for damage, corrosion, or a short to voltage.
- Measure glow plug resistance and the sense-circuit voltage against specification.
- Test the glow plug control module's output and grounds.
- Replace the faulty glow plug or repair the wiring as indicated. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P037F?+
Usually yes once the engine is running, but cold starts will be difficult and cold running rough. Fix it before winter or hard-start conditions leave you stranded.
Can I just clear P037F?+
It will return until the glow plug or its sense circuit is repaired. Clearing only resets the light.
Related codes
Often seen with P037F
Read & clear P037F yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX