P0038: HO2S Heater Control Circuit High (Bank 1 Sensor 2)

What does P0038 mean?

An above-limit heater-control reading is detected at bank 1 sensor 2. This is the rear oxygen sensor used primarily for catalyst monitoring. Depending on how its heater is switched and monitored, an open connection or a circuit short may be relevant; high does not have one universal wiring cause.

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

Common causes

• Short to power in the heater circuit
• Open heater control or return on some systems
• Faulty rear sensor heater

Symptoms

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

Diagnostic focus

High depends on how the manufacturer monitors the heater driver. An open control path or a short can both be relevant; use the factory test rather than assuming a single universal voltage.

Can I keep driving with P0038?

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
• Check the circuit design, then test the heater feed and controlled side separately.
• Repair wiring or replace the correct sensor only when the fault is confirmed

Sources & review

• OBD-Codes.com: P0038
• 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.