P0420 and new down pipe

[tri-pedaler]

Hey all,

I’ve been getting code P0420 for a few months. Put new O2 sensors in and tried different catalytic cleaners, but to no avail. Just picked up a low mileage downpipe and plan to install it this weekend.

Anything else I should try before putting the car under the knife? And any ideas of other stuff I should address while I’m in there?

 

[atlantaM3]

https://www.oreillyauto.com/detail/.../dorman-help-18mm-steel-non-fouler/mtm0/42009

Or some such defouler will be needed for the downstream O2 sensor to clear the code.

 

[TyphoonFiST]

Hey all,

I’ve been getting code P0420 for a few months. Put new O2 sensors in and tried different catalytic cleaners, but to no avail. Just picked up a low mileage downpipe and plan to install it this weekend.

Anything else I should try before putting the car under the knife? And any ideas of other stuff I should address while I’m in there?

Whoosh* End it all

https://whooshmotorsports.com/colle...ant-02-sensor-defouler-j-style-thread-on-bung

https://whooshmotorsports.com/colle...ee-defouler-fiesta-st-focus-st-rs-explorer-st

https://whooshmotorsports.com/colle...ung-w-restrictor-fittings-for-adjustable-flow

 

[tri-pedaler]

Whoosh* End it all

https://whooshmotorsports.com/colle...ant-02-sensor-defouler-j-style-thread-on-bung

https://whooshmotorsports.com/colle...ee-defouler-fiesta-st-focus-st-rs-explorer-st

https://whooshmotorsports.com/colle...ung-w-restrictor-fittings-for-adjustable-flow

Alas, running in a street class for SCCA Autox.

 

[tri-pedaler]

https://www.oreillyauto.com/detail/.../dorman-help-18mm-steel-non-fouler/mtm0/42009

Or some such defouler will be needed for the downstream O2 sensor to clear the code.

Didn’t know about these, thanks. Since I already got a cheap low mileage stock dp I’ll install it, but this seems like a good option if the code still doesn’t clear