P0420 Question

[pin8246]

P0420
FUEL SYS 1 CL
FUEL SYS 2 NA
CALC LOAD (%) 18.0
ECT (F) 201
STFT B1 (%) -4.7
LTFT B1 (%) 7.8
VEH SPEED (MPH) 64
ENG RPM 2104
IAT (F) 57

P0420 Generic
Catalyst System Efficiency Below Threshold (Bank 1)

Alright guys need some help. Story is about a month ago I took my 98 limited in for service cause I did not have time. What they replaced was the timing belt, water pump, downstream O2 sensor, oil change, rotate tires, and wipers. I got this code before the work was done and he said the problem was the O2 sensor so thats why that was replaced. So yesterday I driving for about 2 hours and the same code popped back on. I knew right off the bat it was going to be the same code because something about the shop rubbed me the wrong way. I take a trip back up there today to see exactly what he did, and was stated what I previously posted he did. So here I am again and not going to let him touch it. Where should I start to find the fault. When he told me it was the downstream O2 my first thought is that just checks the cat to make sure its good. I thought it should be the first O2 that should have been changed. Little bit of help would be appreciated if im looking in the wrong direction.

Thanks in advance.

 

[tbst]

I took my O2 sensors out on my Tacoma and torched them with MAP gas. Problem went away.

May not be the best idea for everyone though.

 

[T4R_Finally]

Its definitely the rear sensor that throws that code. And that code means the cat is not performing properly, it doesnt mean the sensor is bad. However, a faulty sensor could be misreading and throwing that code and replacing the sensor will make it stop. If they replaced the sensor, you likely have a bad cat or an exhaust leak.

I was getting the same code, intermittently, and replaced the sensor a few weeks ago. So far, i havent gotten the code again.

 

[pin8246]

So are there any cheap direct bolt on replacements that are recommended. Everything im seeing is 180 and up.

 

[T4R_Finally]

For what, cats? I dont think anything that works is gonna be cheap. If my code comes back, i may go for a urd simulator since i dont have to pass emissions testing and everything seems to be running okay. Search around. You will lots of discussion about cat options.

 

[pin8246]

I was just trying to find an O2 sim that I could put in there to get rid of it, then ill completely get rid of the cat and be done. Just dont want they light to stay on in case a bigger issues trys to show itself.

 

[T4R_Finally]

Do a search for urd simulator. Someone posted a link in one of my threads that had one listed for about 100 bucks.

 

[pin8246]

Yea I found it, but someone stated that the code may come back up. Looked under my truck and its not the orignal cat being used because its a crappy weld job someone did. May just buy another to see what happens. Also been looking for an aftermarket exhaust that has one with it for an upgrade, but cant find that either. Have to go with the full exhaust for that im guessing.

 

[T4R_Finally]

My understanding is that the code should not come back with the sim because the sim is designed to keep the read o2 in normal range in order to prevent the codes even when running performance exhausts for offroading, etc.

 

[dodgetruck]

Interesting... My dodge threw a P0420, and I went ahead and reset it. It stayed off for about 4 months, and it came on again. I reset it for a second time and now, 8 months later, it's still off. I haven't noticed any change in gas mileage or anything. Oh and I passed emissions a few months back too.

 

[T4R_Finally]

Interesting... My dodge threw a P0420, and I went ahead and reset it. It stayed off for about 4 months, and it came on again. I reset it for a second time and now, 8 months later, it's still off. I haven't noticed any change in gas mileage or anything. Oh and I passed emissions a few months back too.

Sometimes it's a CAT problem, sometimes it could just be a faulty sensor, a blip or whatever. The OP already has a new sensor, so it must be something else.

 

[dodgetruck]

Sometimes it's a CAT problem, sometimes it could just be a faulty sensor, a blip or whatever. The OP already has a new sensor, so it must be something else.

Yeah, I was leaning toward the cat being bad on mine, but then it went away and stayed away. I was debating a hi flow cat, but decided not to since it's been staying away. Actually I wouldn't mind just gutting the cat altogether, but I don't have the connections to get it to pass emissions that way lol

 

[T4R_Finally]

Yeah, I was leaning toward the cat being bad on mine, but then it went away and stayed away. I was debating a hi flow cat, but decided not to since it's been staying away. Actually I wouldn't mind just gutting the cat altogether, but I don't have the connections to get it to pass emissions that way lol

They make simulators for Rams too-wink,wink...

I also own a 3rd gen Ram, and i have to say it is the most trouble free, american made vehicle i have ever owned. Which is partly why it is also, by far, the only vehicle i have ever owned for so long. Bought it new off the lot, replaced 1 pcv and just general maint other than that. 7 years and counting.