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P0135 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)

What it means

The heater inside the upstream O2 sensor on bank 1 isn't working. The heater helps the sensor work quickly from a cold start.

Severity: Low

Can I drive it? Safe to drive; emissions and cold-start mileage may suffer.

Common causes (most likely first)

Failed O2 sensor heater element
Blown fuse for O2 heater
Damaged wiring/connector

Likely fixes

Check the fuse
Inspect wiring
Replace the O2 sensor

DIY parts cost

$30–$150

Approximate estimate

Shop repair cost

$150–$400

Approximate estimate, parts + labor

DIY difficulty

Easy to Moderate

Varies by vehicle

Cost ranges are rough, approximate U.S. estimates and vary widely by vehicle, region, and parts brand. Always confirm the diagnosis before buying parts.

Parts you may need

Upstream oxygen sensorCheck price
O2 sensor socketCheck price

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