What this code means

The ECM detected a fault in the front (upstream) heated oxygen sensor on Bank 2. The sensor signal or heater circuit is not providing reliable data for fuel trim control.

Symptoms

• Check Engine Light
• Poor fuel economy
• Rough idle on Bank 2
• Failed emissions test

Common causes

• Faulty O2 sensor Bank 2
• O2 sensor heater failure Bank 2
• Exhaust leak at Bank 2 manifold
• Wiring fault to sensor
• Sensor connector corrosion

Diagnostic steps

1. Test O2 sensor signal Bank 2
2. Test heater circuit resistance
3. Check for exhaust leaks at Bank 2
4. Inspect wiring and connector
5. Compare sensor data between banks

Repair notes

Replace the front heated O2 sensor on Bank 2.

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