O2 Sensor Signal Biased/Stuck Rich Bank 1 Sensor 4

Common symptoms

What you'll notice

• Check for any loose or damaged wiring connections related to the O2 sensor.
• Clean or replace the O2 sensor if it is contaminated or faulty.
• Inspect the exhaust system for any leaks or damage that may be affecting the O2 sensor readings.
• Check the fuel injectors for any clogs or malfunctions, as they can contribute to a rich fuel mixture.
• Perform an engine tune
• up, including replacing spark plugs, air filters, and fuel filters, to optimize the air
• fuel mixture.

Common causes

Most likely first

1. Faulty O2 sensor in Bank 1 Sensor 4
2. Fuel injector malfunction in Bank 1 Sensor 4
3. Engine misfire in Bank 1 Sensor 4
4. Exhaust leak in the vicinity of Bank 1 Sensor 4
5. Issues with the wiring or connectors related to Bank 1 Sensor 4

How to diagnose & fix

Work through it in order

1. Check Engine Light (CEL) or Malfunction Indicator Lamp (MIL) illuminated on the dashboard
2. Decreased fuel efficiency or increased fuel consumption
3. Rough idle or stalling of the engine
4. Hesitation or lack of acceleration
5. Increase in exhaust emissions or the smell of rotten eggs