Code 420 The catalyst seems inefficient (#1).

relaxiknowarchie · Post by **relaxiknowarchie** » Sat Feb 24, 2007 8:30 pm

Hey guys...

Just had my engine light come on on my way home from walmart.

420 The catalyst seems inefficient (#1).

From what I can find this is caused by low back pressure from an exhaust leak between the head and the Catalytic converter. Or possibly the O2 sensor is failing or dirty.

I drive a 2001 R/T that unfortunately hasn't been driving long enough everyday to fully warm up the car (less 5 min drive to work) with the average temperature here being around -10°C for the last 2 months and it only gets a good run once a week.

I do have a Magnaflow high flow cat installed 3 years ago and with 163,000kms on it only burns about a jug of oil every oil change (6000+ km) I haven't noticed any exhaust leaks.

Anyone else have this code? Is it something I should worry about immediately? or can I just wait and see if it gets worse?

04sxt2.0 · Post by **04sxt2.0** » Sat Feb 24, 2007 9:35 pm

you need to replace the cat, the cat has gone bad, either that or get a mil elminator for the rear o2 sensor, and install it. it would probely be the easiest way of getting rid of the code and check engine light

gilly02le · Post by **gilly02le** » Sat Feb 24, 2007 11:21 pm

dead lower o2 sensor.. buy one from ebay or online, bcuz there 137CAD from the dealership... had this happen once... and since my cars exhaust didnt smell bad, i knew my cat was still good.

dblsg · Post by **dblsg** » Sat Feb 24, 2007 11:43 pm

i like code 420

gillyo2le wrote: i knew my cat was still good.

smelly cat FTL!!!

Cbussilver01es · Post by **Cbussilver01es** » Sun Feb 25, 2007 3:36 am

Yea mines no good either.... Its screwin with my performance too... you can just hear and feel the engine choking... it sux

underway · Post by **underway** » Sun Feb 25, 2007 10:29 am

had a gutted cat. and it came on after a long while....now i got rid of the cat. and just welded in some 2.25" pipe and put the o2 in there and it sits kinda far back so it hasnt come on yet i think im good

relaxiknowarchie · Post by **relaxiknowarchie** » Sun Feb 25, 2007 12:33 pm

cool I'll look into this... I have a parts guy at the local dodge who gets me stuff for their cost. so i might get a new cat or I'll see about either a aftermarket high flow or maybe even trying the anti fouling plug adapter mod I saw on here last night. I'll check out all my options first.

thanks I'll keep you updated

Aubrey
Halifax NS

gilly02le · Post by **gilly02le** » Sun Feb 25, 2007 2:49 pm

you should see about getting a high-flow cat if you cat is dead.. and then having a 2.25 inch downpipe made and throw the new cat in there... you'll get better performance with that setup, and not the 25 pound stock cat and dp.

relaxiknowarchie · Post by **relaxiknowarchie** » Sun Feb 25, 2007 8:14 pm

that is what I have now.... I had my map sensor go and plugged up the original cat. so i got a magnaflow high flow cat to replace it. which was $50 cheaper.

update: it was a beautiful day here +13°C washed the car for the first time this year and decided to reset the computer. drove for an hour on the highway and the code never popped back up... so I'm working on the fact that maybe the o2 sensor may have been carboned up from the last 2 months of poor driving conditions and the that the car hasn't had enough time to warm up in the mornings and evenings for the drives to and from work.

who knows....