Mine popped on about 3 weeks ago (14k miles total for me). I had just installed my AMS Lower IC piping, and the clamp popped off - ouch - car died and instant SES light. Undid the battery, pumped the break, tighted the clamp and everything is good.

It's since popped on twice and I've just did the battery again. I have a HF cat too, but it's been on for like 2k miles.

**Update - pretty sure I've got the P0300...

 

I have the Injen Intercooler Pipe Kit and the same thing happened. I blew off the hose, car died and now I get the stupid light. I can reset it with the battery method, but it still comes back on every once in a while. I guess I need to add another tool to my list, scanner here I come.

 

**UPDATE**

Just got the O2 simulator installed and it appears to be working properly (blinking red) Since it didn't come with a long enough grounding wire and I wasn't about to drill into the floor board, I had to go and get some extra wire and lengthen the grounding wire. I grounded it to a screw on the hand brake under the armrest cover where something else is also grounded. Tucked the wires back in under the carpet leaving the O2 simulator standing out so I can see it under the seat. I sure hope that damn SES light doesn't comes back on in the next 200 miles or so. Wish me luck. I'll post back later after I test it out.

 

caymandiver75......where did you purchase the 02 simulator? I also got that same po420 code.........

 

Buschur Racing gave me one since I bought their full exhaust. They have a NO Check Engine Light Policy.

 

Checker carries and lends out an OBDII scan tool. It is nice because you can read the code and clear it without having to reset the radio stations.

Was it cold outside when you got the CEL? Sometime it takes a high flow a little more time to warm up.