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Oxygen (lambda) sensors

P2255 Oxygen sensor: signal or voltage too low (negative current, bank 2, sensor 1)

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P2255 means: Oxygen sensor: signal or voltage too low (negative current, bank 2, sensor 1). The oxygen sensor measures oxygen in the exhaust and the computer sets the fuel mixture by it. OK to drive, but have it checked soon. The repair usually costs about €60–250 in Estonia.

Is it safe to drive?OK to driveOK to drive, but have it checked soon.
Typical repair cost€60–250parts and labour in Estonia

What it means

The oxygen sensor measures oxygen in the exhaust and the computer sets the fuel mixture by it. Sensor 1 sits before the catalytic converter, sensor 2 after it. The computer found the signal wrong, slow or missing. The signal voltage is too low. Usually a wire is broken, a connector is loose or a wire is shorted to ground. Bank 2 is the side of a V engine without cylinder 1.

What you may notice

  • Engine light on
  • Higher fuel consumption
  • Idle may be uneven
  • Emissions may fail the inspection

What could be wrong

  1. 1Connector loose, damp or corroded
  2. 2Wire broken or shorted to ground
  3. 3Faulty oxygen sensor
  4. 4Engine computer fault (rare)

Repair difficulty: Moderate

What you can check yourself

First look at the connector and wiring: anything loose, melted or green with corrosion? Listen for an exhaust leak ahead of the sensor. Check that the sensor wire is intact and the connector is clipped in. You can do the simpler checks yourself.

How we fix it

  1. We read the fault data on the diagnostic tool and check whether the fault is constant
  2. We measure the circuit's supply, ground and signal
  3. We repair the wire or replace the connector
  4. If the wiring is fine, we replace the oxygen sensor

Standard SAE description: O2 Sensor Negative Current Control Circuit Low Bank 2 Sensor 1

This code usually comes with: Check engine lightSee what the light means →

Want a definite answer?

Bring the car to our workshop in Estonia for diagnostics. We read the fault codes, test the sensors and tell you what is wrong. Repair price depends on the work involved, generally €45 per hour.

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Questions

What does fault code P2255 mean?

Oxygen sensor: signal or voltage too low (negative current, bank 2, sensor 1). The oxygen sensor measures oxygen in the exhaust and the computer sets the fuel mixture by it. Sensor 1 sits before the catalytic converter, sensor 2 after it. The computer found the signal wrong, slow or missing. The signal voltage is too low. Usually a wire is broken, a connector is loose or a wire is shorted to ground. Bank 2 is the side of a V engine without cylinder 1.

Can I drive with code P2255?

OK to drive, but have it checked soon.

How much does it cost to fix P2255?

Roughly €60–250 in Estonia. The price depends on exactly what has failed and on the car.

How is P2255 fixed?

We read the fault data on the diagnostic tool and check whether the fault is constant. We measure the circuit's supply, ground and signal. We repair the wire or replace the connector. If the wiring is fine, we replace the oxygen sensor.

Related codes

P2252Oxygen sensor: signal or voltage too low (negative current, bank 1, sensor 1)P2256Oxygen sensor: signal or voltage too high (negative current, bank 2, sensor 1)P2254Oxygen sensor: open circuit (negative current, bank 2, sensor 1)P2257Secondary air system: signal or voltage too low ("A")P2274Oxygen sensor: mixture too lean (bank 1, sensor 3)P2275Oxygen sensor: mixture too rich (bank 1, sensor 3)P2276Oxygen sensor: mixture too lean (bank 2, sensor 3)

Based on AI combined with our hands-on workshop experience and knowledge. This information is general and prices are approximate (Estonian workshop rates). The same code can mean different things on different cars. Only an inspection of the car gives a definite answer.

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