O2 Sensor Circuit High Voltage (Bank 2 Sensor 2)

What it means

The engine computer has seen the bank 2 downstream oxygen sensor voltage stay above the limit, not dropping even during fuel cut on deceleration. This points to a failed sensor or a short in its circuit, and sometimes a truly rich mixture on that bank.

Related codes: P0156P0157P2273P0175P0138

Symptoms4

• Check engine light on.
• Engine runs normally in most cases.
• Fuel smell from the exhaust if the mixture is rich.
• Failed emissions test.

Possible causes5

• Internal failure of the bank 2 downstream oxygen sensor.
• Signal wire shorted to a wire carrying voltage, such as the heater supply.
• Water or corrosion inside the connector under the car.
• A real rich mixture on bank 2, such as a leaking injector.
• Engine computer fault (rare).

How to diagnose5

1. Watch the signal when lifting off the accelerator at speed; the voltage should drop clearly during fuel cut.
2. Unplug the connector and watch the reading; if it stays high with no sensor, the fault is in the wiring or computer.
3. Inspect the connector for water or corrosion.
4. Review bank 2 fuel trims to rule out a rich mixture.
5. Compare its behavior with the bank 1 downstream sensor.

How to fix4

1. Clean and dry the connector and repair any shorted wires.
2. Fix the rich cause on bank 2 if found.
3. Replace the bank 2 downstream oxygen sensor if its voltage stays high during fuel cut.
4. Clear the codes and drive until the sensor and converter tests complete.

Repair cost

In Saudi riyals; the highlighted part is the expected range for this fault.

Cleaning the connector or repairing a wire is cheap, a new sensor is the most common fix, and the cost rises if an injector needs repair.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions