P0037: HO2S Heater Control Circuit Low (Bank 1 Sensor 2)

What does P0037 mean?

The bank 1 downstream oxygen-sensor heater control reads too low. The fault belongs to the heater side of sensor 2, after the catalyst, rather than to its exhaust-oxygen signal. Wiring shorted to ground or an internal heater failure can prevent proper catalyst-monitor warm-up.

Generic OBD-II definition: HO2S Heater Control Circuit Low (Bank 1 Sensor 2). Confirm applicability in your vehicle service information.

Common causes

• Heater control shorted to ground
• Failed rear sensor heater
• Physical damage to the sensor cable

Symptoms

• Check engine light
• Usually little or no change in drivability
• Catalyst monitor may not complete

Diagnostic focus

Focus on the bank 1 sensor 2 heater circuit. A melted wire touching the exhaust can produce this code even if the oxygen-sensing portion still responds normally.

Can I keep driving with P0037?

Severity: Low If the engine runs normally and the light is steady, arrange emissions-system diagnosis. Stop for a flashing light or severe roughness; those symptoms need separate urgent attention.

If the check engine light is flashing or the car runs badly, stop driving and have it checked.

Typical fixes

• Allow the exhaust to cool before inspecting wiring
• Inspect the downstream cable, test for ground shorts, and verify heater power before replacement.
• Repair wiring or replace the correct sensor only when the fault is confirmed

Sources & review

• OBD-Codes.com: P0037
• TroubleCodes.net: generic code definitions

Definitions and diagnostic background checked 2026-11-06. Generic guidance, not a substitute for the service procedure for your exact year, engine, and transmission.