P0030: HO2S Heater Control Circuit (Bank 1 Sensor 1)

What does P0030 mean?

The bank 1 upstream oxygen or air/fuel sensor heater fails its control-circuit check. This heater helps the mixture-feedback sensor start working promptly after a cold start. A failed element, missing power, or an interrupted controlled return can all stop warm-up; the code does not measure the exhaust mixture itself.

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

Common causes

• Open heater element
• Missing fused heater power
• Open or damaged heater-control wire

Symptoms

• Check engine light
• Slow entry into closed-loop fuel control
• Possible decrease in fuel economy

Diagnostic focus

Check the heater power feed and controlled return before condemning the sensor. Several heater codes together can indicate one shared fuse or supply instead of several failed sensors.

Can I keep driving with P0030?

Severity: Medium 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
• Test the cold heater resistance against the vehicle specification, with the sensor disconnected.
• Repair wiring or replace the correct sensor only when the fault is confirmed

Sources & review

• OBD-Codes.com: P0030
• 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.