P0135 Honda Civic
O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1) · Powertrain Code · Low · Repair: Easy
What is P0135?
The heater circuit in the upstream O2 sensor on bank 1 has failed, delaying sensor warm-up.
When the Honda Civic triggers code P0135 (o2 sensor heater circuit malfunction (bank 1, sensor 1)), it typically points to an issue in the powertrain system. Below you'll find the most common causes, symptoms, and repair options specific to the Honda Civic.
This repair is rated easy, meaning basic tools, no lift needed.
Diagnostic data on this page is compiled from publicly available repair resources and technical service bulletins. Always have a qualified mechanic confirm the diagnosis before authorizing repairs on your Honda Civic.
Common Causes on Honda Civic
- Burned out O2 sensor heater circuit (common failure on high-mileage Hondas)
- Blown fuse in O2 sensor heater circuit
- Corroded or damaged O2 sensor heater wiring
- Failed PCM O2 heater driver (rare)
Symptoms
- Check Engine Light on
- Extended warm-up period before closed-loop fueling
- Slightly poor fuel economy during first few minutes of driving
- Failed emissions test
Notes for Honda Civic
O2 sensor heater failure is a normal wear item — typically occurs between 80k-120k miles; always replace with Denso or NGK to match Honda OE quality.