What this code means

The PCM detected a fault in the heated oxygen sensor heater current monitor control circuit for Bank 1 Sensor 1. The heater is used to bring the O2 sensor up to operating temperature quickly.

Symptoms

• Check Engine Light
• Poor cold-start fuel economy
• Extended warmup emissions
• Failed emissions test

Common causes

• Faulty O2 sensor heater element
• Blown heater circuit fuse
• Corroded wiring or connector
• PCM heater driver failure

Diagnostic steps

1. Check O2 sensor heater fuse
2. Test heater circuit resistance
3. Inspect wiring and connectors
4. Test PCM heater output

Repair notes

Replace O2 sensor if heater resistance is out of spec. Check fuse and wiring first.

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