P037D
Glow Plug Sense Circuit
The diagnostic feedback line that monitors glow plug current draw reports a general electrical fault — open, shorted, or out of plausibility. Used to verify each plug actually heats up.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Symptoms
- Glow plug warning light on (often orange coil symbol)
- Hard cold start or no start in cold weather
- White smoke from exhaust during warm-up
Common causes
Ordered by how often each turns out to be the cause.
- Sense circuit failedCommon
Parts involved
- Glow Plug
- Glow Plug Control Module
P037D is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.