Like the title says, will a test pipe turn on a check engine light. I have a 99 a4 and my cat is plugged up from the previous owner. This is my daily driver so i dont want the annoying light on. If the test pipe is going to through cat. codes should i get a high flow cat, and will it through any codes? What companies would you recommend. I dont want the most expensive, but i want a nice piece. thanks

 

im not sure what you mean by plugged up. normally it would put on the chech engine light but theres ways to get around it, you could get a shop to clear that code. also theres a way do it with spark plug non foulers. you should check out ebay just search test pipes they are nice pieces and they are not expensive.

 

the guy i bought the car off drove around with a bad ignition control module causing a misfire causing the plugged cat. I did some more research about testpipes and im going to weld on an extension to the rear 02 sensor keeping it away from the direct flow of exhaust

 

just a little heads up on where not to get your test pipe from. DONT go through eurocode tunning. i bought my evolution racewerks test pipe from them, and it took me having to call and write to evolution personaly. thats only after calling euro code over a dozen times. and even after getting the test pipe i didnt get the two gaskets that i needed. the test pipe is ok helped alot though. good luck

 

yea im not buying a test pipe right now i just gutted the cat until i can afford an exhaust. I had this rattle coming from the turbo so when i pulled the cat i found that the wastegate flapper would not close and the shaft that went through the turbine housing was worn out, along with blown seals and shaft play.