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2005 Chrysler Pacifica, Poor-mileage/MIL
By: David ChampionBy: David from North CarolinaJul 14, 2009 7:42:37 AM3 Replies
This car came in a month or so ago with some catylist efficiency codes.It had been replaced about a year ago with an after market converter which was a good bit smaller than the factory one.I diagnosed as a bad converter and replaced it with an OEM converter and replced the down stream o2 senser.About a week later she brought the car back with the check engine light on and said it started making a wierd noise and runing bad then the light came on.I cleared codes and test drove with the scan tool hooked up.The car ran fine and no light .The o2 data looked good and couldn't find a problem. We orderd another o2 sensor and had her to come back when we got it in to replace it thinking that since it didn't have this code before that maybe we had a defective sensor.Changed sens. cleaed codes took agood long 2 drive cycle test drive,car ran fine all looked good.She took the car.Light back on,same code 2097 downstream fuel trim rich.Same noise running bad poor fuel economy.I still couldn't verify the symtoms other than the code.She can't describe the noise or how the car runs.I thought, well ,I should have relaced the up stream o2 as well so I did.She called that night to say it did it again.I've checked for exhaust leaks and vacuum leaks and found none.I graghed the o2 sensors with the snap on vantage and they checked good. I've never seen a cod for downstream fuel trim before on any car and I thiugt downstream o2s didn't affect fuel trims anyway.Has anyone seen this code on one of these before or hany advice on where I should go from here.She brought it back yesterday and I drove it 50 mi. and another 35 mi. this morn. still no light or running prob..Sorry for such a long post.Thanks for taking time to read this and any help you can offer.I should say she brings the car here for regular service and has had a tune up and BG injetion cleaning.

Updated on Jul 14, 2009 10:14 AM
No,it's never had any misfire codes.I've never had it to act up for me,just keeps turning on the light.Thanks.

Related Repair History
Replaced converter and o2 sensors,up stream and down stream.

Comments posted on Jul 23, 2009 12:22:22 PM
Well,it turns out the light came back on a few days later. Same code.She took it back to the dealer and they put a factory o2 sensor and that fixed it.We replaced it with a Bosh when we did the converter and had put a secound one in later.When we changed the up stream we used one from Dodge.We talked about changing the down stream with an OEM but didn't.The scan data looked good so I didn't see the need.So lesson learned,use OEM o2 sensors on these from now on aftermarket wont work.The OEM cost less than the Bosh I've never had any problem using bosh o2s but from now on I will use the OEM .Thanks for everyone's help.By the way I just read Larry's reply.I'm not the only one who had the same problem.Thanks Larry.

David Champion
Owner
Champion Automotive
Shelby, North Carolina, USA
FIX posted on Jul 14, 2009 2:19:14 PM
Well,I found a problem with the new factory converter.Kody was right,a very small leak will set this code.I used shop air and soapy water and found a weld at the upstream converter flange that was leaking.It allows it to draw in air on deceleration. This flange is just ahead of the upstream o2 sensor.Thanks alot for your time and your help.