neighbor lady husband recently died and has 2006 pacifica 3.5-husband always took to sears-this time I think they got her-has p2097-down stream fuel system 1/2 rich-they put 2 o2 sensors on-not sure if oem or aftermarket.light still comes back on w/same code-alldata says possible causes-ex leak(none),o2 sensor(??),o2 signal/return circuit(switches),fuel contamination(quick trip gas,took sample,looks ok).here is what I have noticed-hooked up actron scan tool and monitoring long/short term fuel trims,st toggles 0 plus/minus 5.0=long term usually 0.0-eng will start to miss very badly almost like running on 3 cyl-stft goes minus 28.5 or higher and long term goes minus 32.4-then as it almost dies,iac /computer/strategy picks up or quits missing and will run fine for about 45-60 seconds then misses again-never dies-code is probably result of cause of miss-what I have done-checked fuel pressure(good)checked spark plugs(has ngk factory ones)plugs are not gas fouled or black-replaced all 6 plugs w/ngks-looked at valves w/bore scope for condition(ok)checked for coolant leak at w/pump area(no crusty orange)wiggled wiring when eng misses to see if concern goes away(did not) road tested for approx 10 miles (never had problem)let idle about 5 minutes and it started missing again-unit is in closed loop-do not know where to go-she is distraught-car has 68k-any help appreciated-I am ford tech and dont know late mopars-HELP-thanks in advance rick

I have seen this on 94-97 Intrepids before with leaking fuel injector o-rings but not on the Pacifica. The long terms job is to bring the short term back as close to 0 as it can so if the short term goes to 28 or more then the long will go up that much or more trying to bring the short term back to 0. So if both are going way minus then it has a serious problem. Once both go to max (33 I believe is max on that model) it will reset after a minute or so back to 0 and if the problem is still there it will go minus again and do the same thing. This is one where I would love to actually watch the scan tool myself. What are the 1/1 and 1/2 (up & down stream) 02 sensors reading while this happens ? They should be at the high end of the voltage scale (either near 1 volt or 3.5 volts depending on the system) as the PCM must think it is very rich and starts taking fuel away to try and get the 02's switching again. I would think both up and downstream 02's would be showing rich. Have you checked on TSB's ?? I can still get into Mopars system and check them even though I dont work for them anymore. Ron

o2 go rich when lt/st go minus-checked tsbs from alldata-wish you were here(haha)

more info-eng will start to miss at transition from open loop to closed loop-had solus scan tool on misfire screen and even though engine was missing(appears to be so)no misfire counts-someone said inj wiring under plenum-looked at that yesterday.HELP-thanks rick

Just saw one like this with 150k on it. Check the pin terminals and wiring from the crank sensor(trans bellhousing LF wheelwell) back up to the PCM. WIGGLE connector at CKP and all 3 wires back to the PCM.

Good luck

Here's a stab in the dark...MAF sensor.

NO MAF on Mopars............

found out that 2 years ago car had new cam/crank sensor and new pcm-also had overlay from crank sensor to pcm-1 st trouble since then-also when got home went over and started and when started to act up-wiggled crank sensor wiring and no change-thanks for all help so far-rick

Sure sounds like a vacuum leak at least at first. Have you checked for one yet? Not sure if they are common on those engines but just had a ford 4L have a vacuum leak at the manifold leak only cold for the first 30 seconds and then would run fine. Fuel trims were -40 and counting for the first 30 secs then went back to zero. After doing the intake was fine. Was surprised how fast the leak sealed up but showed up after awhile by smoke testing the manifold. And had no codes.

hey rick,, drop a note and say the pcm is the problem here
just a rumor i heard , pass it along ,

Yea, need to paint a picture...

taking car to mopar dealer-will let everyone know what it was-lady says thanks to all and you all have 1 extra prayer said for you by her-thanks from me also-last thing today as iat and coolant started out same value on scan tool-iat 74 coolant 74-eng started fit at coolant 92 and iat at 78-only other thing saw that load was 100% iac trying to idle motor back up-thanks again rick

This Pacifica sets multiple O2 codes. Originally it set a upstream O2 code and later set catalyst efficiency code. I replaced both sensors to make sure they were both good even though they seemed to be switching ok on the scanner. Now it came back with a P2097, downsteam fuel rich 1/2. I gave the O2 readings below and the fuel trim numbers. Any suggestion? Could it have a bad converter?

Thanks.

Related Repair History
I replaced the upstream and downstream o2 sensors. It had previously set upstream o2 code and catalyst efficiency code P0420.

Randy Hiebner
Technician
Tri County Automotive
Henderson, Nebraska, USA
FIX posted on Jan 25, 2010 4:38:02 PM
Thanks too all who responded. I had installed Bosch O2 sensors. I for know have replaced the downstream sensor with an OE Chrysler sensor and the problem hasn't reoccured.

Thanks again, Randy.
Manifold Vacuum Readings

Idle: 18.9 in.


Computer Codes & Descriptions

P2097- Downstream fuel system rich 1/2


Other Test Results

Upstream V. - 2.5-3.4 v
Upstream Desired V. - 2.06 v
Downstream V. - 3.11 v
Short adapt - -3% to 2%
Long term at idle - 12.5%
Long term at 2000 RPM - 9.8%

5 Replies Received (Hide Replies)Please only use this feature to report severe guidelines violations.

Reply 1 Clifford from Texas Jan 20, 2010 10:47:30 AMin the absence of an exhaust leak this code is almost always an aftermarket (usually bosch) o2 sensor. check the integrity of the entire o2 circuit and if good shoot the o2 sensor.

p.s. chrysler converters are failing at an astounding rate. when you replace the o2 prepare for a return of the p0420

Reply 2 from New Mexico Jan 20, 2010 11:19:16 AM check temp inlet and outlet on cat. should be 10% hotter on outlet


Reply 3 Matthew from Illinois Jan 20, 2010 11:37:47 AMIt is not the converter. This is a downstream sensor monitor failure. 2 things to check: 1. make sure there are NO misfires: reason extra reactants in the exhaust will cause a higher downstream voltage 2. Check the downstream heater operation (make sure the chassis ground wire for the heater has nearly zero volts on it) reason: PCM supplied bias will "bleed" over into the signal sense when the sensor cools off (making the internal resistance higher)


Reply 4 Gilbert from Massachusetts Jan 21, 2010 5:01:13 AMThis code can set if a new cat has been put on. If this is the case, the monitor should pass after the new cat gets about 500 miles on it. The other reason it would fail is the use of aftermarket O2 sensors. Mopars need factory O2s to work properly. Also, after replacing O2s on Mopars you need to do a battery disconnect to force the PCM to learn O2 heater resistance values. Failure to do this step will result in improper O2 heater operation.


Reply 5 Charles from Massachusetts Jan 21, 2010 6:43:41 AM also make sure they are plugged into the proper connectors

this info borrowed from Iatn.net

another

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.

thanks wheels up--here at ford if we see o2 failures we 1st look at aftermarket o2s-even though we have been told that Bosch makes ford and Motorcraft o2s-there is something very different about them-example-Windstar fails to pass I/M o2 w/aftermarket customer does drives cycle 4-5 times-never sets to take to emissions-installed m/c and passes 1 st time on drive cycle-will let everyone know problem when I find out-thanks again to everyone

car was taken to mopar dealer locally and after rechecking all I did they put in 2 new mopar o2 sensors and unit is now fixed-thanks for everyones help-rick