Rep Power: 0

I have a 2001 Honda Civic EX Sedan 1.7L I had the infamous P0420 code pop on. I replaced the old converter with a magna flow universal fit to save some and possibly free up some flow for extra MPG. However the light came back on with the same code. I ran the diagnostic and it came back that the cat was inefficient. I contacted a master tech and he said the universal fit cats even though they may be CARB and 50 state legal won't turn off the CEL. Aynobody have any experience with this?

 
Rep Power: 519

Coin?

You got what you paid for.
There's a reason a factory cat is expensive. It works.

Some will, some won't. Never consistent enough to guarantee a damn thing as far as keeping the computer happy. Many that will pass initially won't last through the 1 year warranty before the light and code comes back. Then your warranty won't cover installation, just the part.

First choice for a cat is always factory.
Second choice is CARB/California approved aftermarket unit.

No 3rd choice as far as I'm concerned.
If a customer wants a cheap cat, they can go be mad at someone else when it doesn't work out.

NOTE: No matter how good or how new your cat is, a poorly running engine can ruin a brand new cat in just a matter of a few minutes.

A good cat does not restrict exhaust flow.
The correct cat is designed to flow far more CFM than the engine can push....unless or until the cat gets restricted.