well i got ALLLLLLL this stuff on my truck fixed and pulled upper intake (EGR port was completly clogged) and even cleaned all that out good!! The truck has been running great and finally got the CEL light off. Its been about 2 weeks and the CEL light came on again today...ran the code and its a P0420 bank 1. the truck is still running rich and using more gas than normal and that was a big part of my prob. before...since i've changed the plugs and wire (to motorcraft) the MPG's have somewhat improved.....from what the link below says im thinking it might be a front O2 sensor but was kinda lookin for some other opinions also....thanks!!


P0420 Error Code: Catalyst System Efficiency Below Threshold (Bank 1)

 

The cats are probably worn out or damaged. A bad O2 sensor is possible but less likely.

If the sensors are old, replacing the upstream O2 is not a bad first guess, especially considering that it might also help the poor fuel economy. It's way cheaper than starting by replacing the cats first but you might end up doing that anyway. The downstream O2 sensor leads an easier life than the upstream and may never need replacement.

 

yeah i was thinking upstream too.......and i hope the cat isnt goin bad but the truck does have almost 300k on it so....i've also noticed that it does seem a lil restricted wot...i just figure its me goin into this 4cyl and used to driving my 4.0...i guess i can start there and hopefully that'll fix it..i saw a bosch premium OE replacement on advance auto for $47.99 so that's not to bad! i just know that conn. is gonna be a pain to get too!! lol

 

Thats the code for roll up a joint man!!!!!! Your truck is just wantin some herb lol.

 

x2 on medicating the truck

 

LOL!!!! well i prefer TLC.......lol!!

 

Well that works to lmao. But it really sounds like the cats are on the way out. Do you have emissions testing?

 

Replace the cats josh. Same thing was wrong with the contour. Replaced both and fixed that problem.

 

no this is alabama!! LOL!!! we're gonna get there though!!

just never known a bad cat to cause a vehicle to run rich and use fuel.....but who knows...im still gonna start with front o2 and see what happens.

 

The cats in the contour caused the car to run rich or lean I cant remember. I think it was rich. Either way I'd replace them. Or take them to a shop and see if you can just remove them all together. It might be cheaper.

 

when you have a miss fire or running rich and there is extra fuel in the exhaust it kills cats. replace your cats and call it a day. i just had this same code on 3 cars at work i replaced the cats and there were plugged as hell and solved all the problems.


your 02 sensors are probably reading low so they are dumping more fuel into the system thinking that the cat needs it to run properly. i wouldnt waist your time with 02 sensors i would just do the cats

 

Both very valid points but why spend $300+ for cats when i can buy a $50 o2 that may fix the whole problem? if not then i can worry about the cats i just wanna start with the simplest and cheapest thing first.

 

Its bound to need it anyway. Fix the o2 then see how it goes, but more then likely with how many miles are on the truck. they need to be replaced.

 

Well since you don't have emissions testing why don't you just cut the cats out and weld in a straight pipe in there place?

 

true dat! lol

well even though this is alabama it still is illegal and a pretty hefty fine if caught...plus i dont like having a CEL on in case there is another problem that occurs and wouldnt know it.