I just got a highflow cat about 3 months ago,no problems, then the SES light came on..... Im thinking it is the o2 sensor, and will be going to Auto Zone to see if they call get the code for me. When I go there where exactly do they hook their tool upto? Just in case they have no idea what Im talking about?

And also where do I buy the new piece to keep the SES light from coming on?

Thanks alot.

Also what are a few of the codes. What am I looking for here?

the connection is made on the drivers side of the dash - on the right side close to the center console.

P0420 is the Inefficient Cat code. That's probably what you got.

cool ,thanks

After you find out that's what it is, the you can try the fix I did.

Here is the thread -

https://www.evolutionm.net/forums/sh...ad.php?t=62524

Starts at post #14 No CEL for 10K+ miles

I had the very same thing happen to me. The light came on twice even after pulling the negative battery terminal. After the second time it hasn't come back on and it has been over 400 miles.

Yep......It was the PO 420 code.........rest it,,,,,,,,,came back on,,,,,,disconected the battery,,,,hasnt came back for 3 days.

Thanks again

Hey silvrevo,

Do you have the stock muffler with the hi-flow cat?

The reason is this: I originally had a Borla exhuast that I installed along with the hi-flow cat and a downpipe. I ran this setup for months with no problems.

Then, I got a fixit ticket for loud exhaust so I put back my stock exhaust just last week. Everything was fine for about 7 days, then the SES light came on. I disconnected the battery terminal to reset the ECU last night and since then it's been gone.

If your setup includes a stock muffler along with your hi-flow cat, then I think I had the same thing happen except my light came on faster (7 days compared to your few months). I am thinking that if you get an aftermarket exhaust that flows a bit better, that should eliminate the SES light better.

Brent

Nope......I have a HKS DP.....HF Cat,,,,,,stock IP,,and Works Axel back.

Thinking of getting a cat back now ,,,,cause it is rather loud ,it was cool sounding,but now its rather loud.

Looking at gett a Magna flow muffler.

Hmmm....Interesting...So I guess it is safe to assume that either a hi-flow cat OR a straight test pipe MAY trip the SES light....

Plus, I don't think it's vendor dependent either, it just might happen whenever a hi-flow cat or a testpipe is installed...

Brent

my CEL came on the other day from my UR hi flow cat. disconnected the battery and it went off.

I have the Helix HF cat and no problems 5K miles on it.