Why CEL fix when catted...

[moose]

Just curious. My Helix DP came with a CEL fix, but it's a catted one. Assuming the high flow cat is decently efficient, why would a CEL fix be required at all? Isn't the purpose of the rear O2 simply to monitor that the cat's doing its job?

[sti4u2nv]

My catted helix DP did not come with CEL fix. Maybe it was included by accident. I wouldn't put it in unless you through a CEL.

[moose]

Thanks for the reply. I read something about setting a code BECAUSE of the CEL fix (something about slow readings?), so didn't want to install it unless required.

[GTscoob]

is it a splice-fix or the mechanical?

My APS turboback had one cat left and I still would get the PO420 "Rear Cat Inefficiency" code until I wired up the Perrin 02 Simulator.

I would just go with the mechanical CEL fix that spaces the 02 sensor farther away from the exhaust stream. If you need one I've got a spare and I know Scott at SoG keeps them in stock.

[moose]

It's the mechanical one that spaces the sensor out about an inch or so. I have it so will install if needed, but couldn't figure out if the high flow cat was efficient enough to keep it from triggering anything.