Hi i have a 2002 Saturn Vue awd auto, v6... the other day it threw a DTC code of P0421 which is the warm up catalyst effecieny below threshold ( bank 1)...so i am assuming that the cat. is bad and needs replaced, or could there be something else.....
Another thing that i have noticed is that on my scan tool....(CANOBD2) and on this i can view advanced dtc's, it has an option to view vehicle id, i am assuming that is the VIN, if it is it shows a different VIN which would tell me that a used pcm was put in and not reprogrammed...and suggestions...

 

No, I really don't have a suggestion. Although this following page does;
http://www.obd-codes.com/p0421
Interesting! It is an obd-II code, in genral the same code reads on any number of cars.
Catalytic converter going bad, O2 sensor bad or a missfire possibly caused by a bad plug.
The last is the easiest to check.
Personally I have nver had an O2 sensor fail on anything ranging from a number of 1980 cars to what ever I am driving now. And I still own 2 1980 cars.
I have had catalytic converters fail and if you live in a salt environment that would seem to be a possibility.
I have used a generic aftermarket supposedly high flow catalytic converter for all my smog system replacements. Have not had a bit of problems with it, and it has worked correctly for every year car I have had it installed on. About a C note and a half welded into the exhaust system. Muffler shops locally all seem to carry the same one.

 

Scott ...

The comment UnclJohn wrote above is valid - a generic aftermarket cat will work on your Saturn - I've got one on mine. I had hit a piece of road junk, and it opened my old converter like a can-opener. I did not replace my O2 sensor. $170 usd here in Mississippi, and about an hour in the muffler shop .....

 

just replaced the rear 02 sensor on my 97sc2 to clear out this code.
if you're near 100k or so its not a stretch that it's fouled.

Much cheaper than buying and paying for a cat +installation

 

Thanks for the advice....i am hoping to go out there this morning and tap on the cat. with a rubber mallet to see if i hear anything... i have an extra o2 sensor and i will try that too....then i will post the results....i can tell you that when you drive it sounds like it has a glass pack on it....sounds strange....
oh and by the way, i live here in rural west virginia.....

 

Thanks for the advice...i will try to replace the o2 first, i have an extra one... i also heard that you can take a rubber mallet and tap on the cat to see if it has broken pieces in it....i this true.....and n ot to change topics, but if a code scanner shows a different vehicle id than what on the dash, does that mean the PCM was replaced.....


after i try to cat i will post the reults

 

Ok i changed out the sensors, tapped on the cat with a rubber malletand it sounded fine...thecode popped up onceand now it popped up 2 codes...P0700 and P1779...so i have no clue what the problem is...

 

P0700
P0700 indicates that the engine control module (ECM) received a message from the transmission control module (TCM) to turn on the
malfunction indicator lamp (MIL) telltale due to a transmission related OBD II failure.

P1779
When the ECM sends the TCM a driver requested torque signal that is invalid, DTC P1779 will set.

Are you sure you didn't knock any connectors loose?
Seems like too much of a coincidence....does it shift funny?
You can try putting the old O2 back in there, clearing the codes, and seeing if the tranny code comes back....

Also -- not clear --- did the Cat code come back?

The info I got above was from

http://saturnfans3.saturnfans.com/~saturnfa/forums/showthread.php?t=147435

and

http://www.saturnfans.com/forums/sho...d.php?t=137696

there are some good vue specific pdfs posted there

 

oh sorry, no the cat code did not come back... and the code for the transmission is only the second time....i wasnt around that area of the saturn so i dont think i knocked anything loose....but i can tell u that i do know that there is or was this little white cap or holder braket on the shifter where it attaches to the top of the tranny...it isnt there, that part has been wired on, so maybe that explains that code popping up.... but i will look at your links...
thanks

 

ok, losing it here

you had the tranny code before?

you never mentioned it

???