What it means
Glow plug indicator drive line stuck high — short to B+. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
The glow plug indicator control circuit carries the module’s command to the dashboard glow lamp. P037B sets when the module detects the indicator line staying above its expected level, such as from a short to battery voltage or a disconnected signal path.
Common causes
Most likely first.
- Short to B+
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
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
How to diagnose it
- Record freeze-frame data and check the commanded glow plug indicator state when the fault occurs.
- Compare scan-tool command data with the dashboard lamp’s behavior, including during a cold start.
- Inspect the indicator wire and connectors for contact with a power feed, chafing, water ingress, corrosion, or pushed-back pins.
- With the circuit isolated as directed by the manufacturer, test for a short to battery voltage and check connector continuity.
- If the wiring checks out, test the indicator driver and control module against the manufacturer's specification.
Common fixes
- Repair wiring that is pinched or chafed against a power source.
- Dry, clean, and repair connector terminals or seals affected by water or corrosion.
- Restore a loose or pushed-back terminal and secure the connector.
- Replace the failed indicator driver or control module if testing identifies it.
Can I keep driving?
The fault can keep the dashboard glow lamp from reliably showing its commanded state, while cold starting may be difficult and produce white smoke during warm-up. Avoid prolonged cranking in cold conditions.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.