Oxygen (lambda) sensors

P2239 Oxygen sensor: signal or voltage too high (positive current, bank 1, sensor 1)

By: Diagno editorial team · Updated: 2026-10-15

P2239 means: Oxygen sensor: signal or voltage too high (positive current, bank 1, 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 high. Usually a wire is shorted to power, the ground is broken or the part itself has failed.

What you may notice

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

What could be wrong

1Connector loose, damp or corroded
2Wire shorted to power or ground broken
3Faulty oxygen sensor
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

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

Standard SAE description: O2 Sensor Positive Current Control Circuit High Bank 1 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.

Book a diagnostic check

Questions

What does fault code P2239 mean?

Oxygen sensor: signal or voltage too high (positive current, bank 1, 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 high. Usually a wire is shorted to power, the ground is broken or the part itself has failed.

Can I drive with code P2239?

OK to drive, but have it checked soon.

How much does it cost to fix P2239?

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

How is P2239 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.

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.