P0135
Get Serviced SoonFix: Medium — get serviced in 1–2 weeksO2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1) — The pre-cat O2 sensor heater isn't working.
Dashboard light triggered
Check Engine LightWhat to do
Replace the upstream O2 sensor. The heater helps it reach operating temp quickly. Safe to drive but may affect fuel economy.
Common causes
- Failed O2 sensor (heater element)
- Wiring/connector issue
Estimated repair cost
$100–$300
Exact cost depends on the cause, your vehicle, and labor rates in your area.
What to tell your mechanic
Use this script so you sound informed and get a clear diagnosis before agreeing to repairs:
“Code P0135, O2 heater circuit bank 1 sensor 1. Can you confirm it's the sensor and not a wiring issue before we replace it?”
About the Check Engine Light
Code P0135 triggers the Check Engine Light. Indicates an issue with the engine or emissions system. Could range from a loose gas cap to a serious engine misfire.
Read full Check Engine Light guideFrequently asked questions
- What does OBD code P0135 mean?
- O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1) — The pre-cat O2 sensor heater isn't working.
- What dashboard light does P0135 trigger?
- P0135 triggers the Check Engine Light.
- How serious is P0135?
- Severity: yellow. Fix priority: Medium — get serviced in 1–2 weeks.
- How much does it cost to fix P0135?
- Repair costs typically range from $100–$300. The exact cost depends on the root cause and your vehicle.
Related OBD codes (same dashboard light)
These codes also trigger the Check Engine Light: