Heated Oxygen Sensor Exchange Banks Swapped

What this code means

The ECU detected that the upstream heated oxygen sensor connectors for Bank 1 and Bank 2 appear to be swapped. The sensor signals do not correspond to the expected bank, likely due to incorrect wiring after service.

Symptoms

• Check Engine Light
• Poor fuel economy
• Rough running
• Failed emissions test

Common causes

• O2 sensor connectors swapped after repair
• Wiring crossed between banks
• Incorrect sensor installation during service

Diagnostic steps

1. Verify which O2 sensor connector goes to which bank
2. Trace wiring from each sensor to ECU
3. Induce a rich/lean condition on one bank and verify correct sensor responds
4. Check sensor connector routing

Repair notes

Swap the O2 sensor connectors back to the correct bank positions.

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