What this code means

The downstream O2 sensor on Bank 1 is reading high voltage consistently.

Symptoms

• Check Engine Light
• Failed emissions
• May indicate catalyst failure

Common causes

• Faulty sensor
• Catalytic converter failure
• Rich running condition

Diagnostic steps

1. Test sensor voltage
2. Check catalyst efficiency
3. Monitor upstream vs downstream O2 patterns

Repair notes

Replace sensor. If catalyst failed, replace catalytic converter.

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