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P0420 Diagnostic Trouble Code Discussion for January 2020

Catalyst Efficiency Below Normal (Bank 1)

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Trouble Ticket Help Requests for DTC P0420
Help Request Posted
2015 Isuzu NPR-HD 5.2L MIL Lamp on VIN: JALC4W167F
P0420: Catalyst system efficiency. 2015 Isuzu NPR-HD 5.2L engine code p0420 recurring after normal regen. if you perform a slow regen you will get no code and be code free for 160 miles till next requested regen and you get code p0420. clear code and do slow regen no code do a normal regen ...
January 07, 2020