p0420 AFTER replacing cats..HELP

[kosmo101]

So this nightmare continues. A few months ago got a check engine light. Pulled the MAF, cleaned it. Still no good. Got one from a junkyard. Same thing. Bought a new one.. same thing. Brought to a muffler shop and replaced both cats for big $$$.

Pull away from the shop and within one mile..check engine light comes on!!

GRRR

What now? Im furious..and need to get the truck inspected.

Any ideas??

Thanks kev

 

[Stick Figure]

Did you test or replace the catalytic efficiency (o2) sensor?

http://www.ncttora.com/fsm/1996/SIL...2rmsour/2002/024runne/di/eg5vzfe/cip0420o.pdf

there is the actual trouble shooting info for the P0420 code. That is assuming that is the code you have since you didn't really say what code you were throwing.

 

[kosmo101]

Cant say what was tested..my fault for not asking the shop. They hooked it up to diag tool and said both cats were bad in the readings. No mention of 02 sensors.

I would think this the same P0420 code but didnt check as they were closed when I went back. They stayed late to replace cats...and only mgr was there so nothing he could have done mechanically.

I have to call tomorrow to ask if they rechecked the code after they finished work and if they reset it or what. I just was convinced that this would be gone after dumping so much cash. I gather not.

So what would you ask if you were me..if they checked the 02 sensor?

Sure appreciate it
thank you

 

[Baja Runner]

P0420 usually means O2 sensor... that should have been the first thing replaced.

I've always had a difficult time testing O2 sensors. You have to have a multimeter that is able to read the step outputs. The heater circut is easy to test though its not usually the part that fails.

O2 sensors usually need to be replaced ever 50 to 75k. Make sure you buy OEM-style Denso, and DO NOT USE BOSCH.

 

[kosmo101]

How difficult is it to change this out? Would advance or autozone or oreilleys have this?

Will search here for a writeup... thanks

 

[Nelsonmd]

How difficult is it to change this out? Would advance or autozone or oreilleys have this?

Will search here for a writeup... thanks

Look in the tutorial and reference documentation sticky for info on the O2 sensors. ONLY BUY DENSO! Part number in the link from the sticky. Everything you need to know is there.