I have a 07 ram with the 5.7 and I installed OBX long tube headers with high flow cats and Flowmaster mufflers and now the truck keeps throwing codes P0420 and P0133. I have replaced all 4 O2 sensors with NTK brand sensor and still throws the codes. I would really appreciate any info.

Thanks.

 

You increased airflow with those changes. Was the battery disconnected while doing the swap? If not, go try that. It may take a while for the codes to pop back up, but you'll know if it was just computer confusion then.


SJ03

 

Yes I unhooked the battery for about a half hour and the codes still came back.

 

Of course you have codes. Exhaust is outside PCM programmed threshold. Nothing wrong with old sensors. You either need a tuner to disable the post cat O2s or do the $5 non foulers trick.

BTW, the chambered mufflers just undid all the free flowing the headers and cats created. Unless using the wing plate series 10s. Proven fact Flowmaster 40, 44, 50, etc. chambered "flow" worse than stock...

 

I will try the non fouler trick and see what that does. The code says it is sensor number 1? Isn't that the pre cat sensor? What muffler would you recommend to run instead of the Flowmaster 50? Thanks for info.

 

The P0420 is showing not enough difference between pre and post cats. Non foulers is the popular fix.

The P0133 is a problem with the pre cat (upstream) sensor. Either you nicked a wire or more likely you have an exhaust leak BEFORE this sensor. Bad header weld, torn gasket during install, sh*tty weld???

The P0420 isn't a big deal, just an annoying CEL. But the P0133 needs attention as it will effect A/F mix and will result in degraded performance and MPG.

Lots of muffler choices, just stay clear of the ones that cheat and use chambers for better sound. Magnaflow, Flowmaster 10, Aero 3030 or just about anything Cherry Bomb makes are popular choices.

 

Thanks for the help.