I have been told this could be a "tube" stoped up in the motor. Has anyone had this problem before? The codes are T0420-CAT and t0401 EXTT or EXH GAS
Check engine light is on on 2000 Mercury Cougar
Can you provide us with the code that caused the light to come on? Are yo talking about an EGR tube?
The P0401 code can be from a plugged EGR tube or port, however I don't know if that will cause the P0420 code. Here is some info for both of the codes:
The codes are T0420 and T0401