Code 0420

widowmaker · **Posted:** Sat Aug 04, 2007 7:09 am

I got the CEL last week and pulled a code 0420.
"P0420 Catalytic converter system, bank 1 – efficiency below threshold Catalytic converter, wiring, HO2S 2"

It had been idling rough for a few weeks and I thought it might need some new spark plugs, but now I suspect this is the problem. My question is concerning the next step. Should I start replacing O2 sensors and hope for a lucky outcome or bite the bullet a take it to the shop? If they start replacing the catalytic converters...(3 of them?)...it could run into some bucks.

2002 Jeep Liberty
3.7L
Limited
225,000 miles

drew4406 · **Posted:** Sat Aug 04, 2007 10:41 am

i got the same code in july at 194,000. started w/ o2 sensors frist local auto parts stores could not get L/R or R/F w/clips. I cleared the code, and then it came, talked w/mech. truned out to be the left cat. Could not find it the afertmarket for size and location per ---- ca. smog rules. Had to buy it from dealer started at 750 got it down to 605 out the door
hope you have better luck i hate that code

WoodysKJ · **Posted:** Sat Aug 04, 2007 11:16 am

Widowmaker,

Try here for the cats and o2 sensors.

pretty good prices. local shop can install if you can't

http://www.trademotion.com/partlocator/index.cfm?action=getJointLocator&siteid=214583&chapter=&sectionids=7,2489&groupid=60222&make=17&model=Liberty&year=2004&catalogid=1&displayCatalogid=0

Good luck
do a serch for the o2 sensors, tuff to find on this site. Range in 18.00 -20.00 bucks.

replacing them is no big deal, special socket and they back out. new ones clear codes give it a try.

SoDakJeep · **Posted:** Sat Aug 04, 2007 5:07 pm

When I got that code it was the left downstream 02 sensor. The wires were broken or something. That sensor was only 22 or 23 bucks I think so its a cheap fix and you might see a gain in mpg.

Neal · **Posted:** Sat Aug 04, 2007 5:51 pm

Make sure to check for broken wire or connector problem on that sensor, I had a problem with the wire being broken off

widowmaker · **Posted:** Sun Aug 05, 2007 6:50 am

Thanks guys, I checked the wiring and all looks good. I've decided to replace the o2 sensors, as this is a cheaper gamble. If that fails, I'll hand her over to the shop and take my medicine.
Thanks again

Jeepjeepster · **Posted:** Sun Aug 05, 2007 1:45 pm

Youve got 225,000 on your liberty!!?! Have you had any other problems out of it? :shock:

widowmaker · **Posted:** Sun Aug 05, 2007 5:14 pm

Jeepjeepster wrote:

Youve got 225,000 on your liberty!!?! Have you had any other problems out of it? :shock:

Best vehicle I've ever owned. I lost the transmission at 170.000 miles and had it rebuilt. It turned out to be one valve that went bad, but since they had it open, I had it rebuilt. Zero engine problems, but had the air conditioner condensing coil replaced last month. It burns about a quart of oil every 2000 miles and my daughter is driving it to college this fall. She'll probably forget to check the oil and that will be the death of her...the libby that is.

I drive a CRD now and hope to beat the miles on that gasser. Hope

Code 0420

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