Catalyst Temperature Sensor Circuit Bank 1 Sensor 2

Where it lives

For P042A, the sensor sits on the circuit this code reports. The description of P042A puts it on bank 1.

Check these first

• A failed rear catalyst temperature sensor on bank 1
• An open or short in the rear sensor circuit
• Corrosion at the rear sensor connector
• A converter running hot from a rich condition
• An ECM fault on the rear sensor input

What to do next

1. Read the rear sensor temperature on a scan tool
2. Check the rear sensor circuit for an open or short
3. Inspect the rear sensor connector for corrosion
4. Check fuel trims and misfires for a rich condition
5. Replace the rear sensor if the reading is implausible
6. Clear the code and retest

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