Junior Member
Code PO420 after Cobb DP
I have a 2011 WRX.I sometime back installed a Cobb catted DP & flashed to Stage 2 93 oct.Car was running fine without any problems.
Recently I installed an AEM intake & flashed to Stage2+AEM 93 oct & twice now the car has been throwing a PO420 code(Catalytic system efficiency below threshold).This happens during normal cruising speeds.I cleared it with the AP.
Any help on why this is happening would be appreciated.What can be done to fix the issue.
Junior Member
monday bump
Junior Member
bump,anyone?
Senior Member
I would got into ATR and just look at the map because as far as I know that should be defeated.
Senior Member
Agree with snoopy. Make sure the DTC is defeated and then I would flash the base map just to be sure.
04 WRX wagon, 6-speed w/ R180, AP V2, Greddy T67-25g rotated kit, FMIC, 720cc injectors (850cc or bigger injectors awaiting funds), Parallel fuel rails w/ -6AN braided lines, Walbro 255lph, PERRIN 3-port EBCS, TGV's deleted/ported/polished, phenolic TB & TGV spacers, Grimmspeed ceramic coated UP, Greddy catless DP, Borla Hush CB, Dual core radiator, COBB F&R antisways, Grimmspeed brake brace, Innovate WB O2, Greddy boost gauge, Greddy EGT gauge, Prosport elec. fuel and oil pressure gauges
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