Should I be getting a code?

[dlacey82]

I am getting a PO420 Catalyst efficiency code, it happens after about 40 miles of highway driving when I get off the freeway and I am idling, it smells like it is dumping way too much fuel at idle and then the SES light comes on.

I have the typical bolt ons but stock heads and cam.

It had hypertech tuning on it, which I read in this section is not the best for an M6 which is what it is.

I took the tune off it today and went back to all the stock settings and it hasn't thrown the code since and I drove the same route all days.

Anyone else have this same issue? Just wondering if thats really what it is. Seems to me like a tune shouldn't result in a code.

[Knight]

Using handheld tuners have been known to cause problems. They really don't tune, just make a few adjustments, and usually don't help much. A tune from Frost (a sponser) would be a better way to go, or a dyno tune. If you plan to do any other mods, I'd wait until doing them to get a tune though.

[35th-ANV-SS]

It makes sense to me that it doesn't happen on the highway. Your O2 sensors aren't switching as much as they are on the highway as opposed to driving around town in stop and go traffic.

[Firebirdjones]

Since you reflashed, it may take a few trips to reset the code again. Sounds to me like you might have a cat going south.

[dlacey82]

I forgot to add that the cat is brand new, which is why I assumed that it wasn't really that to start with.

I have driven 300+ miles w/o Hypertech tune and have not got the code again.

With it on it was setting it around 40 miles and sometimes less.

Thanks for the help fellas!

[Knight]

I forgot to add that the cat is brand new, which is why I assumed that it wasn't really that to start with.

I have driven 300+ miles w/o Hypertech tune and have not got the code again.

With it on it was setting it around 40 miles and sometimes less.

Thanks for the help fellas!

[dlacey82]

Also, I checked out the Frost website today, looks like the way to go and very reasonably priced.

[Knight]

Also, I checked out the Frost website today, looks like the way to go and very reasonably priced.

You won't be dissappointed.