P0135 fault code: what it means

P0135: Bank 1 upstream O2 sensor heater circuit fault; the sensor takes too long to warm up.

Engine and gearbox (powertrain) · Minor

Usual causes, most likely first

burnt-out heater in the front O2 sensor
corroded or damaged connector
blown heater fuse

P0135 by make

Haval

Front O2 sensor heater circuit.

Usual causes: failed sensor heater; wiring or fuse

Honda

Heater circuit fault in the front air-fuel ratio sensor (bank 1 sensor 1). On Hondas the heater element inside the sensor usually fails.

Usual causes: front air-fuel ratio sensor heater failed; blown A/F heater fuse; sensor wiring or connector

Hyundai

Front oxygen sensor heater circuit fault (bank 1 sensor 1).

Usual causes: failed front oxygen sensor heater; wiring or connector fault; blown heater fuse

MG

Front O2 sensor heater circuit.

Usual causes: failed sensor heater; wiring or fuse

Suzuki

Front O2 sensor heater circuit. Very common on older Suzukis.

Usual causes: failed O2 sensor heater; blown heater fuse; wiring

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 P0135 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.