P037D
Glow Plug Sense Circuit
Diesel glow plug
Generic OBD-II
Medium
What it means
P037D is a diesel code meaning the glow plug sensing/feedback circuit isn't reading correctly. Glow plugs pre-heat the cylinders for cold starting, so a fault here mainly shows up as harder cold starts and rough cold running — usually from a failed glow plug, its wiring, or the glow plug control module, rather than an engine mechanical problem.
Medium
Can I keep driving? Drivable once warm — expect harder cold starting and possible rough running/white smoke until the engine warms up.
Common symptoms
What you'll notice
- Check-engine light (and often the glow plug/wait-to-start light) on
- Hard starting when cold, longer cranking
- Rough running and possible white smoke right after a cold start
- May start and run normally once warm
Common causes
Most likely first
- Faulty glow plug or glow plug sensing/feedback circuitLikely
- Open, shorted, or corroded wiring in the glow plug sense circuitCommon
- Poor electrical connection at a glow plug or the glow plug control moduleCommon
- Faulty glow plug control moduleLess often
How to diagnose & fix
Work through it in order
- Identify which glow plug/sense circuit is flagged and inspect its wiring and connectors.
- Measure glow plug resistance and check for battery voltage during the pre-glow cycle.
- Inspect the glow plug control module connections and grounds.
- Replace the faulty glow plug or repair the sense-circuit wiring, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with P037D?+
Yes once the engine is running — the main effect is harder cold starting and rougher cold running. Fix it before winter to avoid no-cold-start problems.
Can I just clear P037D?+
It returns if the glow plug or sense-circuit fault is still present. Repair the circuit first.
Related codes
Often seen with P037D
Read & clear P037D 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