P0164

What it means

P0164 means the engine control unit has detected a voltage that is too high in the oxygen sensor circuit for Bank 2, Sensor 3. Bank 2 is the side of the engine that does not contain cylinder number 1, and Sensor 3 is normally a further downstream sensor, such as one fitted after a second catalytic converter. The control unit saw a signal voltage above the expected range for longer than its test allows, which points to a wiring, connector or sensor fault. Sensor layout varies by model and engine, so confirm which sensor is Bank 2 Sensor 3 on the vehicle.

Symptoms

• Engine management light on
• Usually no noticeable change in driveability
• Possible slight rise in fuel consumption if the fault affects fuel trim monitoring
• Failed emissions test or readiness monitors not completing
• Other oxygen sensor or catalyst codes stored alongside it

Possible causes

• Faulty oxygen sensor (Bank 2 Sensor 3) giving a high or stuck signallikely
• Signal wire shorted to a voltage supply or to another wire in the sensor harnesslikely
• Damaged, corroded or contaminated connector terminals at the sensor or plugpossible
• Chafed or heat-damaged wiring near the exhaustpossible
• Contaminated sensor from coolant, oil or silicone ingresspossible
• Poor sensor ground or reference circuit faultrare
• Engine control unit faultrare

How to diagnose

1. Confirm the code with a scan tool, then read the freeze frame data and note any other stored codes, especially other oxygen sensor codes.
2. Identify which sensor is Bank 2 Sensor 3 for this engine, using the manufacturer's information, as the layout varies by model.
3. Visually inspect the sensor wiring and connector for chafing, heat damage, melting, water ingress and corrosion.
4. With the engine warm, view the live data for the sensor and see whether the voltage is stuck high or responds to changes in load and throttle.
5. Unplug the sensor and check the signal, reference and ground circuits for shorts to voltage, shorts to other wires and for continuity, following the wiring diagram.
6. Check the sensor heater circuit and supply, where fitted, for correct operation and for any wiring cross-over between circuits.
7. Inspect the exhaust for leaks near the sensor and check for signs of contamination on the sensor tip.
8. If wiring and connectors are sound, compare the sensor's response with the specification or a known good sensor before condemning the sensor or control unit.

How to fix

• Replace the Bank 2 Sensor 3 oxygen sensor if it is faulty or contaminated, using the correct type for the vehicle.
• Repair or replace damaged wiring, and secure it away from hot exhaust parts.
• Clean or replace corroded or damaged connectors and terminals.
• Find and fix the source of any contamination, such as a coolant or oil leak, before fitting a new sensor.
• Repair any exhaust leak near the sensor.
• If all circuits and the sensor test fine, have the control unit checked and repaired or replaced as advised by the manufacturer.

Can I keep driving?

Nearby codes

• P0163GenericO2 Sensor Circuit Low Voltage Bank 2 Sensor 3
• P0165GenericO2 Sensor Circuit Slow Response Bank 2 Sensor 3