My 'SES' light came on yesterday. (only 5600 miles on the car). I pulled the code and sure enough, the cat is the cause. I have a MiniMania header and HRP exhaust on the car. It has been on since about 1800 miles. Shouldn't the cat last a little longer than that? Or is the cat they use a cheap one not designed for the rigors of performance driving? I guess I go back to the stock header.

I checked the MM website and they say that the header is sold for off road use only, but still has a cat. I guess that is for stock racing classes only?

MM header

Oh well, live and learn.

 

why not just buy an aftermarket cat?

 

I'll give you our stupid cat free!

 

What was the code, Catalyst System Efficiency Below Threshold?

 

>>What was the code, Catalyst System Efficiency Below Threshold?

Yes, that was the code. It was reset and has not turned on yet, but I only drove it a few miles since.

Is that something else besides the cat converter?

 

Well, the rear O2 sensor is monitoring how well the cat is working and the code is set as a result of that feedback. Since you have an aftermarket cat, I'd say the most logical cause is that cat just isn't designed to do as good a job as the stock one. After that, I'd check the condition of the rear O2 sensor and the wiring associated with it. This is a common occurence with VW 1.8T's:

http://forums.vwvortex.com/zerothread?id=663057

 

Ah My old friend, P0420. I knew him well when I had my Random Technologies cat. Your cat is fine. An O2 simulator will make him go away but the car should run fine with that light on, just annoying.

--
Cheese




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>>Well, the rear O2 sensor is monitoring how well the cat is working and the code is set as a result of that feedback. Since you have an aftermarket cat, I'd say the most logical cause is that cat just isn't designed to do as good a job as the stock one. After that, I'd check the condition of the rear O2 sensor and the wiring associated with it. This is a common occurence with VW 1.8T's:
>>
>>http://forums.vwvortex.com/zerothread?id=663057

OK, I'm IMPRESSED. Henceforth I will pay VERY close attention to all you say oh sapient one.......and THANK YOU!!