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P0042 — O2 Sensor Heater Control Circuit (Bank 1 Sensor 3)

Third O2 sensor heater circuit on bank 1 (vehicles with dual cats).

Severity: MediumRepair: $80-$250Difficulty: Easy

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Common symptoms of P0042

Common causes of P0042

Repair cost & difficulty

Typical cost to fix P0042: $80-$250 · Difficulty: Easy

Pro tip: Third sensor is rare — only on vehicles with two catalytic converters in series.

Vehicles commonly affected

Vehicles with dual catalytic converters

Related trouble codes

P0036P0030

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ScanFixAI is a diagnostic aid, not a substitute for professional repair. Cost estimates are typical ranges and vary by vehicle and region.