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P0139 — O2 Sensor Slow Response (Bank 1 Sensor 2)

Downstream O2 sensor on bank 1 is switching too slowly.

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

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Common symptoms of P0139

Common causes of P0139

Repair cost & difficulty

Typical cost to fix P0139: $80-$250 · Difficulty: Easy

Pro tip: Slow downstream sensor should be replaced. It's relatively cheap insurance against a false P0420.

Vehicles commonly affected

All makes

Related trouble codes

P0136P0140P0420

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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.