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Home >> Subaru >> 2006 >> Outback R >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Diagnostic Trouble Code (DTC) Detecting Criteria (H4SO) >> Diagnostic Trouble Code (DTC) Detecting Criteria >> DTC P0420 Catalyst System Efficiency Below Threshold (Bank 1) >> Diagnostic Method

Diagnostic Method

After establishing the execution conditions, calculate the front oxygen (A/F) sensor lambda deviation cumulative value per 128 milliseconds (Σ |(sglmdn - sglmdn-i )|) and rear oxygen sensor output voltage deviation cumulative value (Σ |(ro2sadn - ro2sadn-i )|), and when the front oxygen (A/F) sensor lambda deviation cumulative value (Σ |(sglmdn - sglmdn-i )|) becomes higher than the predetermined value, calculate the diagnostic value.

Judge as NG when the malfunction criteria below are met. Judge as OK if the criteria below are not met.

Judgment Value 

JUDGMENT VALUE CHART

Malfunction Criteria Threshold Value
Σ |(ro2sadn - ro2sadn-1 )| / Σ |(sglmdn - sglmdn-i )| > 1.0

Time Needed for Diagnosis:  30 - 55 seconds

Malfunction Indicator Light Illumination:  Illuminates when malfunction occurs in 2 continuous driving cycles.