P0135
Low severityO2 Sensor Heater Circuit (Bank 1, Sensor 1)
Quick answer
P0135 (O2 Sensor Heater Circuit (Bank 1, Sensor 1)) means: The heater in the upstream oxygen sensor on bank 1 isn't working as expected. Not urgent, but affects emissions readiness. Typical Malaysia repair cost: RM80–RM300 (approximate).
Symptoms
- •Check engine light
- •Slightly worse economy
Likely causes
- •Failed oxygen sensor
- •Heater circuit wiring/fuse
- •Connector corrosion
Can I drive?
Not urgent, but affects emissions readiness.
Estimated repair cost (Malaysia)
RM80–RM300 (approximate)
Diagnostic guide (for mechanics)
Work through these in order — cheapest and safest checks first, before replacing expensive parts.
1. Test the O2 heater circuit
This is the sensor's internal heater, not the sensing element. Check heater resistance and supply voltage.
Test: Multimeter: heater element resistance; battery voltage at the heater feed.
Expected: Resistance within a few–tens of ohms (per spec); ~battery voltage present.
2. Check fuse, relay and ground
No heater power often traces to a blown fuse or bad ground rather than the sensor.
Test: Check the relevant fuse/relay and heater ground.
Expected: Fuse intact, good ground.
Tools: OBD-II scan tool · Multimeter
When to escalate: If supply and ground are good but the heater is open, replace the oxygen sensor.
This is general information, not a diagnosis. AutoMalaya OBD helps explain your car’s actual scan data; a qualified mechanic may still need to inspect the vehicle.