What this code means

General malfunction in the upstream oxygen sensor circuit for Bank 1.

Symptoms

• Check Engine Light
• Poor fuel economy
• Rough idle
• Failed emissions

Common causes

• Faulty O2 sensor
• Exhaust leak near sensor
• Wiring damage
• Fuel system issue affecting sensor

Diagnostic steps

1. Test O2 sensor signal voltage (should oscillate 0.1-0.9V)
2. Check for exhaust leaks
3. Inspect wiring
4. Monitor sensor response time

Repair notes

Replace O2 sensor. Check for exhaust leaks first.

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