How many cats do I have? 4.0

2005 4.0L, was getting some 02 sensor error codes. The PO installed 02 sensor spacers, so I took them out and now I have p0420 and p0430 error codes. I made sure that the cats off the headers were intact.. but the rear cats were hollow or the bulged area downstream from the second 02 sensors was hollow.
My question is, should there be cats back there too? So four cats total? If so, what’s the best way to fix... take to a shop and have new cats welded in? Full exhaust systems are like 800 bucks...

 

I think you guys have 4 but I could be wrong...should be easy to tell if you crawl underneath though. When I got the P0420 code it was for the front cat but I went ahead and replaced both (only 2 on my 1st gen) just to be safe. OEM cats are crazy expensive but if you don't live in a strict emissions state you can get away with much cheaper aftermarket ones.

Just don't go too cheap...cheap cats use very little of the material inside that filters the emissions and will crap out on you again quickly (and throw the codes once more). Magnaflow makes highly recommended aftermarket cats, more expensive than other aftermarket brands but way cheaper than OEM. I would check them out.

 

4 I believe.

 

Does your area do yearly emissions testing?

 

4 cats total, but after the 2nd cats, there are no more O2 sensors.

Downstream O2 sensors mean the sensors after the first cats. Could you replace those, and see if your problem goes away?

 

I could replace them, but my ultraguage shows very good voltage on all 4 so I doubt that’s my issue. Before I got into all this I had a error code for low voltage at the downstream (second) 02 sensors, and the ultraguage confirmed that (like .001 volts regularly). I think the error was p1037. Removing the sensor spacers fixed that problem, but now I have p0420 and p0430. My state (MN) doesn’t do emissions tests. I do also have an exhaust leak that I could try to fix, it’s way downstream tho passed the cats and sensors and I dunno how I’ll fix it, I replaced the donut gasket but it still leaks.

 

Yes there should be four cats total, one each in the exhaust manifolds and one per side on the ypipe

 

You could try the URD o2 sensor simulator.

 

"the P0420 code stands for “Catalyst System Efficiency Below Threshold (Bank 1).” When you receive a P0420 code it means your catalytic converter is not operating at maximum efficiency. Usually this means your catalytic converter needs to be replaced or there is a problem with your O2 (oxygen) sensors."

The cats on the Y pipe dont have sensors after them. I replaced my Y pipe with a catless one, and have had no codes for 2 years. Even had emissions done, and no issues. Usually if you google the code (or search on here) then you can find some answers - like replacing your O2 sensors

 

Good catch, having a catless y-pipe shouldnt cause you any o2 sensor codes. The problem is likely the cats in your manifolds are on their way out. Sounds like the previous owner encountered this as well since he put o2 sensor extensions on. Putting those back on would be a cheap fix, which effectively would be the same thing as running a o2 simulator. To truly fix the problem, you likely need new cats for the headers

 

I actually bought the truck needing head gaskets, and I got them done and replaced one of the manifold cats back then (5 years ago). Because it was blown out. Bow they both look perfect from the back (y pipe side), but I’ll assume there’s no other way to check if they’re good or not right? I checked my oil and coolant and they’re both clean and correct levels.

 

Anymore than 4 and you're just some creepy cat lady.

 

I love cats but I'd put that limit at 3 before becoming a crazy cat lady

 

Im not aware of any other way to check them.. If it's not causing drivability issues, and you dont have to worry about emissions in your state, just throw the o2 bung extensions back on and call it a day. That fix will be way easier than replacing the cats in the manifolds. Either o2 bung extensions, or o2 simulator and call it a day imo. Wont gain any performance by replacing the cat, so i say ride it out as long as you can till it causes you issues. We have an FJ cruiser with the 4.0 in the family and it has 280k miles. Also has the same p0420 and 0430 codes due to bad cats. I threw a URD O2 simulator in there a few months back, andit hasnt thrown a CEL since. No drivability issues either

 

My 05 has 281k and I was getting error code p0137 (02 sensor low voltage) with the 02 spacers, that’s why I took them out and it did fix that error, but gave me these new ones also.
Well if anyone out there has had these errors p0420 and p0430 and fixed them without adding a simulator please chime in, otherwise I might go that route as well.

 

Buy a set of long tube headers, y-pipe, add the o2 simulator and call it a day.

 

Only thing that will fix those codes is new cats (unless it's being thrown for another reason like an exhaust leak), otherwise you have to trick the ECU into thinking the cats are good via an O2 simulator.

 

Do you think a leak down passed the cats and manifolds might be to blame? I can work on that, it’s a fairly bad one.