OBD-II diagnostic trouble code
P0135Safe to drive
O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
The electric heater built into the front bank-1 oxygen sensor has failed, which delays the sensor reaching operating temperature and can hurt cold-start emissions and fuel economy.
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Code names are compiled from open/standardized SAE and ISO references. Explanations, symptoms, causes and fixes are original. Covers generic (P0/C0/B0/U0) codes only — manufacturer-specific codes are planned for a future update.
Frequently asked questions
Can I drive with P0135?
In most cases, yes — P0135 is generally not an urgent safety issue and the car is usually safe to drive for a while. Still, get it checked soon, since the underlying cause can affect fuel economy or emissions the longer it's left.
How much does it cost to fix P0135?
The cost varies too much by cause and vehicle to give a single figure here — a diagnosis will narrow it down.
What causes P0135?
Reviewed by Artyom SemenovAutomotive Editor · Fact-checked by Yauheni Kapliarchuk, Editor-in-Chief