Code P420.
 

Catalyst Efficiency below threshold ( bank 1 ) Got this today, what do i need to change to fix this ?

Hi there


Think yours Lambda is gone/knackered,but without the removing and checking is just guessing

If its your car mapped,you can contact your mapper which can check and remove this CEL,but for now you will have bad MPG with this fault for now

If its knackered would recommend replace


Jura

Cheers. I openport map my own car. I have just been reading up on the P0420 code. I am first going to clear the code with my scanner, then see if it comes back. If it does maybe a denso sensor is due or maybe a new downpipe, i say that as my exhaust seems louder ( maybe more free flow through the Sti sports cat ?. Yeah i can turn the light off myself no prob, but my car will prob fail the MOT in October due to high emissions.

Yes if you can clear the code with the your scanner and after you will see.

Decatted DP will flow more than any sport cat,with the decatted exhaust you can pass MOT,but seems only on few of them,but in general decat exhaust will not pass MOT

I think in the Romraider is option to disable this error to coming up


Jura

I had this on mine after fitting the 2nd decat, some are lucky and it doesn't flag the cel (my previous WRX PPP didn't) but doesn't necessarily mean there's a problem at all.

If you can opensource map, it's easy just to turn off on the fault code tab of romraider as Jura said.

Cheers Andy. My WRX has the 2nd de cat already anyway. About a month or 6 weeks ago i fitted a STI sport cat downpipe but have had no CEL in that time. For now i have cleared the code with my OBD scanner, if it returns yes i will clear the code on romraider and reflash my map.