What are the common causes of P037B?

P037B: Failing ignition coil, spark plug, or spark plug wire. P037B: Faulty crankshaft or camshaft position sensor. P037B: Wiring or connector damage in the ignition circuit. P037B: Low compression or engine mechanical wear. P037B: Incorrect ignition timing or a stretched timing chain.

P037B: Read misfire counts and freeze frame data with an OBD-II scanner. P037B: Test spark output and inspect spark plugs and coils. P037B: Check crankshaft and camshaft position sensor signals while cranking. P037B: Swap suspect ignition parts between cylinders to see if the fault moves. P037B: Compression test if the issue persists on the same cylinder.

P037B

Glow Plug/Heater Indicator Control Circuit High

System: Ignition and misfire (P code)
Lamp: Check Engine Light
Category: Powertrain - Ignition

What it means

P037B stands for Glow Plug/Heater Indicator Control Circuit High. P037B is a P code, so the fault sits in the engine, transmission and emissions systems. For P037B, the second digit places it in ignition and misfire. For P037B, work through the cause list below, cheapest checks first.

What to check first

For P037B, check the wiring and connector on this circuit first, since a broken terminal gives the same reading as a failed part.

Check these first

P037B: Failing ignition coil, spark plug, or spark plug wire
P037B: Faulty crankshaft or camshaft position sensor
P037B: Wiring or connector damage in the ignition circuit
P037B: Low compression or engine mechanical wear
P037B: Incorrect ignition timing or a stretched timing chain

What to do next

P037B belongs to the ignition and misfire system. These are the general steps for P037B, and the exact cause on your vehicle can differ.

P037B: Read misfire counts and freeze frame data with an OBD-II scanner
P037B: Test spark output and inspect spark plugs and coils
P037B: Check crankshaft and camshaft position sensor signals while cranking
P037B: Swap suspect ignition parts between cylinders to see if the fault moves
P037B: Compression test if the issue persists on the same cylinder

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Updated

Generic SAE J2012 definition. Last updated 2026-08-30.