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Home >> Subaru >> 2018 >> WRX STI >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (Diagnostics) (2 Of 4) (STI) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P0420: Catalyst System Efficiency Below Threshold Bank 1 >> Execution Condition
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Execution Condition

EXECUTION CONDITION - EXCEPT FOR TYPE RA

Secondary parameters Execution condition
Battery voltage ≥ 10.9 V
Barometric pressure ≥ 75.1kPa (563mmHg, 22.2inHg)
Amount of intake air ≥ 10g/s (0.35oz/s)
and
< 50g/s (1.76oz/s)
Estimated catalyst temperature ≥ 430°C (806°F)
Vehicle speed ≥ 40km/h (24.9MPH)
Estimated temperature of the rear oxygen sensor element ≥ 500°C (932°F)
Sub feedback In operation
Experiences the following conditions after experiencing all of the above conditions
Rear oxygen output voltage after fuel cut (bank 1)* ≥ 0.55V

* Five seconds or more of fuel cut.

EXECUTION CONDITION - TYPE RA

Secondary parameters Execution condition
Battery voltage ≥ 10.9 V
Barometric pressure ≥ 75.06 kPa (563 mmHg, 22.2 inHg)
Amount of intake air < 8.5g/s (0.3oz/s)
Accelerator pedal position ≥ While idling
Rear oxygen output voltage after fuel cut < 0.15V
Estimated catalyst temperature ≥ 480°C (896°F)
Estimated temperature of the rear oxygen sensor element ≥ 500°C (932°F)
(*Fuel shut-off function from the integrated intake air amount during fuel cut) ≥ 28g (0.99oz)
Fuel shut-off function from above Not in operation

* Five seconds or more of fuel cut.