What this code means

General malfunction in the downstream O2 sensor circuit for Bank 1.

Symptoms

• Check Engine Light
• Failed emissions test
• Reduced catalyst monitoring

Common causes

• Faulty downstream O2 sensor
• Wiring damage
• Exhaust leak after catalyst

Diagnostic steps

1. Test O2 sensor voltage
2. Inspect wiring
3. Check for exhaust leaks after cat

Repair notes

Replace downstream O2 sensor.

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