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Enter a 5-character code such as P0420, P0301, or P0457.

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Codes starting with P are engine and transmission, B are body, C are chassis, and U are network communication. A 0 as the second character means a generic code shared by all makes; a 1 means a manufacturer-specific code, so its meaning depends on your brand.

A steady check engine light usually means get it checked soon. A flashing check engine light means an active misfire: reduce speed and stop driving as soon as it is safe.

That doesn't look like an OBD-II code

A valid code is one letter (P, B, C, or U) followed by four characters, for example P0420.

P0135 Oxygen sensor heater circuit (Bank 1 Sensor 1)

Can I drive with P0135?

Drive

Safe to keep driving normally. Fix it when convenient.

The car runs normally. The sensor just takes longer to start working after a cold start, so fuel economy and emissions are slightly worse until the engine warms up. The light stays on, which fails an emissions inspection.

What does P0135 mean?

The heater built into the upstream oxygen sensor on bank 1 is not working. The heater warms the sensor so it can read the exhaust soon after a cold start. Sensor 1 is the one before the catalytic converter, and bank 1 is the side of the engine with cylinder 1.

What causes P0135?

The heater inside the sensor burning out is most common. Check the related fuse first, since that is free and takes a minute.

  1. Failed oxygen sensor (heater burned out)
  2. Blown oxygen sensor heater fuse
  3. Damaged wiring or connector
  4. Engine computer fault (rare)

How much does it cost to fix P0135?

$150 – $450

Oxygen sensor replacement: $150–$450. Doing it yourself, the part costs about $30–$120, plus a special oxygen sensor socket. Old sensors can be seized, so use penetrating oil, and buy the sensor listed for bank 1 sensor 1.

What are the symptoms of P0135, and how can I confirm it?

Usually none besides the light, though fuel economy can drop slightly. Check the fuse, then unplug the sensor and measure resistance across its two heater pins with a multimeter. A low reading, often under 20 ohms, is normal; no reading means the heater failed. P0141 is the same fault on the downstream sensor.

Will P0135 fail an emissions test, and should I clear it?

It fails any OBD-II based inspection while the light is on, and the oxygen sensor monitors will not finish. After replacing the sensor or fuse, clear the code and drive normally for a few days. If P0135 returns, check the wiring and connector for melted or broken wires near the exhaust.

Confirm the code yourself

A low-cost scanner lets you read the code, clear it, and see if it comes back before paying for a diagnosis.

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