P0038 fault code: what it means

P0038: Rear oxygen sensor heater circuit high, bank 1 sensor 2.

Engine and gearbox (powertrain) · Minor

Usual causes, most likely first

shorted sensor heater
wiring shorted to voltage
failed sensor

P0038 by make

Mazda

Rear oxygen sensor (HO2S) heater circuit high. No drive symptom; catalyst monitor will not run.

Usual causes: rear O2 sensor heater shorted; wiring short to power

Nissan

Rear oxygen sensor (HO2S2) heater circuit high (shorted). No drive symptom, but catalyst monitoring will not complete.

Usual causes: rear O2 sensor heater shorted; wiring shorted

What the repair usually costs

Air-fuel ratio / front O2 sensor replace (upstream)NZ$270–NZ$750 · A$260–A$730
O2 sensor replace (downstream / after cat)NZ$180–NZ$480 · A$180–A$460

Not sure what P0038 means on your car? Ask Credov.

Before you clear it

Write the code down or photograph the scanner first. A code that comes straight back after clearing points to a fault that is still there. A car whose codes were cleared just before you arrived may be hiding one: the scanner's readiness monitors show "not ready" for a while after codes are cleared.

Researched by Credov from manufacturer and workshop sources. A fault code points to where a fault may be; a workshop confirms it with a diagnosis. Browse all fault codes.