I get P0420 "Catalyst sytem Efficency below threshold" on my WRX STI PPP -02.
Do I really need a CEL fix if i use prodrive piggyback ECU?


I have:

K&N panel filter, Prodrive exhaust, Gems piggyback ECU, walbro pump.

 

Bump.

 

Bump...

 

cel fix or proper map ie ecutek as prodrive piggyback cannot take decat
martin

 

cel fix it is then!
I think i's a 2200ohm resitor required to put the fake temperature within spec.

Andy

 

I have the real prodrive system with cat in the downpipe.

 

From your set up I'm surprised you get a P0420 CEL. Recommend you get it checked out or if you know what your doing do a DIY mechanical or electronic CEL fix as described here:

http://www.scoobypedia.co.uk/index.php/Knowledge/CELFix

I noticed above a post above the 'resistor fix'. As per the referenced article this will not fix your reported CEL. Resistor fix is for P0546 - Exhaust Gas Temperature Sensor Circuit Malfunction (High Input).

Hope this helps.
-Steve.

 

Crispy Duck is of course right. Ignore what I said.

Andy

 

The prodrive cat can still sometimes be just not quite good or fast heating enough to avoid the CEL. I would suspect a PPP ecutek map has the values massaged a little without preventing the CEL altogether.

Paul

 

Cats also do fail over time if you're unlucky. I have a sports cat which was throwing the 0420 CEL, and fitted a resistor / capacitor fix (do a search, I posted the how's and where's in here probably 3 years ago). May well be related that my system with the sports cat comfortably failed MOT emmissions and therefore needs replacing.

 

you could also have an air leak in to exhaust system which will also bring it on and the sti's did have a problem on a few with an exhaust joint leaking.