P037A
Glow Plug/Heater Indicator Control Circuit Low
The driver circuit for the glow plug warning indicator (the dashboard glow lamp) is stuck low — short to ground or stuck-low driver.
- Check engine light: Yes
- Emissions related: No
- 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.
- Short to groundCommon
- Connector pins corroded - high contact resistanceLess likely
- Harness chafing through insulationLess likely
Parts involved
- Glow Plug Indicator
P037A 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.