I have a 1998 Dakota 5.2 that in Sept. of 2010 I had a magnaflow exhaust system put on it.They installed a Catco converter with magnaflow muffler and pipes.Single pipe into muffler, duel out.Since this was installed every year afterwards I'll get a check engine light and a PO420 code which is a catalytic converter code.In 2011 they replaced the Catco with another Catco and then 1 year later another check engine light with same code so they talked me into a IMCO converter which they thought would solve the problem.Here it is a year later and I get the engine light with the same code.3 converters in 3 years and now it needs another.I've been emailing Magnaflow but they haven't come up with an answer yet.I notice with this system that whenever I decelerate it will Cackle and Pop out the exhaust.Don't that mean that there is a lack of back pressure.Seems to me like this could be my problem.Engine runs great,performs well and sounds great with this exhaust,but this check engine light every year with a catalytic code has got to stop.Any help here will be appreciated.

 

I would say everything is ok I'm guessing they placed the downstream O2 in the wrong location it does matter were its located.

 

What is the downstream 02.And where is it supposed to be located.

 

You have a 98 so your downstream is not required, it can be zip tied to the frame rail.