Catalytic Converter Problem

[deep thought 42]

So my car just popped with the code P0421 (Catalyst efficiency below normal levels). After a little research, I found that excessive oil burning can lead to failure of the converter. I have noticed my car's oil levels to be dropping faster than usual lately and my mileage isn't so good. So I assume I have to replace the valve cover gaskets along with my converter. Is there anything else that could possibly be the issue? I'd just like to know what else to look into before going through with repairs.

[bronxbombr]

i got good prices on the cat if you need it.

[01blackG]

If your valve cover isnt visually leaking then that isnt the problem. I have just over 200,000 miles on mine with original engine. I burn 1 quart every 3000 to 4000 miles.

With that said your CAT may be loaded down with burnt oil if you have the same thing going on. Only way to fix it is to buy a new CAT and rebuild the engine.
But also that code can be produced if the mesh flex muffler is rusted thru. So inspect your exuast also for any rusted thru spots. If you find any before the CAT get those fixed before buying a new CAT.

[DTP]

So my car just popped with the code P0421 (Catalyst efficiency below normal levels). After a little research, I found that excessive oil burning can lead to failure of the converter. I have noticed my car's oil levels to be dropping faster than usual lately and my mileage isn't so good. So I assume I have to replace the valve cover gaskets along with my converter. Is there anything else that could possibly be the issue? I'd just like to know what else to look into before going through with repairs.

Are you leaking oil onto the outside of the engine block? Any misfires?

After idling, can you give your car gas and see if blue smoke comes from the tail pipe? <-- may be valve seals

[deep thought 42]

I don't see any leaks on the block and the smoke from the back is white from the cold. I'll crawl under when it gets warmer to check for any rusted through spots. It's just too damn cold out right now to get any work done.

[deep thought 42]

Huh, so the light went away on it's own. I guess it was just the cold getting to my car.

[silversurfer]

no rebuild the head its the valve seals have them clean the head resurface and install new valve seals this should stop all leaks , first do a cylinder leak down test to see if the rings are bad if not do the head reconditioning its heaper and you should get more miles out of her.and change the oil more often.this is what causes the failure of the seals and use good oil.

[01blackG]

Huh, so the light went away on it's own. I guess it was just the cold getting to my car.


The engine lights will go off on there own sometimes, after days of being on. It doesnt mean the problem is fixed.

[Silver_8G]

Ive got the same code. What cat usally goes bad. Also im thinking it was from the old engine leaking oil.