chavita28

I guys I need your help. What's the best way of figuring out weather or not I have a clogged cat? My CEL is on and I think it's a possibility thats the source. Is there anyway to test and see if it's clogged or bad? It's a 99 f-150 5.4 and I belive it has 4 cats

Almighty

Get the code pulled at auto zone

chavita28

I did and it's coding for EGR and 02 sensor

udderbrudder

Any exhaust leaks at manifold? This can cause both of your codes if it's on L/side.

ColtRice17

Egr is the little metal pipe that brings exhaust from your geaders/ exhaust manifold and brings it back uo into yiur throttle body. The O2 sensor is just below your 3 bolt flange.

chavita28

I have a small leak at start up but goes away when the truck warms up. But I have had the leak
Long before the cel ever came up could they still be tied together?

ColtRice17

Yes if the leak is significant. You may be able to seal it with something like braz it shut with a cheap torch. If the leak is big enough than than it will throw them off by drawint in outside air which is cleaner and it will detect poor back pressure

chavita28

Ok I'll have to track down that leak and see if its a broken stud. But can you explain how come the leak never set the CEL before?

ColtRice17

It may not have been leaking bad enough. Could be as simple as the fact this summer is hot and when you have a leak and its hot exhaust starts hemoraging.
(I don't think I spelled that correctly)

chavita28

Well that makes sense