Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0135-00: O2 Sensor Heater Circuit (Bank 1/Sensor 1): General Description
The normal operating temperature of the Heated Oxygen Sensor (HO2S) ranges from 350 to 850°C (662 to 1562°F). The Heated Oxygen Sensor (HO2S) heater greatly decreases the amount of time required for fuel control to become active. The PCM provides a pulse width modulated control signal to adjust current through the heater. When the Heated Oxygen Sensor (HO2S) is cold, the value of the resistance is low and the current in the circuit is high. On the contrary, if the temperature in the resistor of the Heated Oxygen Sensor (HO2S) rises, the current drops gradually.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.