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Home >> Subaru >> 2021 >> Forester Touring >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System (Diagnostics) (2 Of 4) >> Diagnostic Procedure With Diagnostic Trouble Code (DTC) >> DTC P0420: Catalyst System Efficiency Below Threshold Bank 1 >> General Description >> Execution Condition
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Execution Condition

Secondary parameters Execution condition
Battery voltage
Barometric pressure
Amount of intake air
Accelerator pedal position
Rear oxygen output voltage after fuel cut
Estimated catalyst temperature
Rear oxygen element impedance
(Integrated intake air amount during fuel cut Fuel shut-off function thereafter)
A/F element impedance
10.9 V or more
75.1kPa (563mmHg, 22.2 inHg) or more
Less than 8.6g/s (0.3oz/s)
While idling
0.15V or less
500°C (932°F) or more
185ft or less
More than 18g (0.63oz)
Not in operation
75Ω or less