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1990 Dodge Omni What keeps causing my O2 sensor to fail?

Tiny
KATI
  • MEMBER
  • 1990 DODGE OMNI
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 90,000 MILES
I've had my Omni for about a year now. When I got it, it wasn't running. The catalytic converter was plugged, so it would start, run extremely rough for a few seconds while exhaust poured out of the engine, then die. We fixed that problem, but ever since my O2 sensors have been failing (or getting stuck in rich position). I'm about to replace #3, but obviously something is causing them to fail. My engine idles rough, my dash gets nice and squeaky at stop lights. I also tend to get terrible gas mileage. On a trip to the beach my old Omni used a quarter tank, this Omni uses a half. I'm going on a thousand mile trip in a week and need help quick! I also took it through DEQ today for a courtesy check, which it failed horribly due to the O2 sensor. Thanks. Message me for any other questions.
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Friday, May 2nd, 2008 AT 7:08 PM

10 Replies

Tiny
LEGITIMATE007
  • MECHANIC
  • 5,121 POSTS
You said you fixed the problem, did you replace the catalyctic converter?
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Saturday, May 3rd, 2008 AT 8:25 AM
Tiny
LEGITIMATE007
  • MECHANIC
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Is the engine abnormally hot?
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Saturday, May 3rd, 2008 AT 8:26 AM
Tiny
KATI
  • MEMBER
  • 6 POSTS
No it never runs abnormally hot, it's just that about every 4 months or so my check engine light comes on after a bunch of highway driving and tells me it's my O2 sensor, so I replace it. But I really don't want to be replacing such an expensive part every four months. There's no reason for it. Something must be causing them to fail. Right?
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Saturday, May 3rd, 2008 AT 11:47 AM
Tiny
LEGITIMATE007
  • MECHANIC
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Yes definitely, did you say that your catylictic converter was messing up and you fixed it? Did you replace it? Because I think heat is backing up and burning out the o2.
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Saturday, May 3rd, 2008 AT 3:16 PM
Tiny
KATI
  • MEMBER
  • 6 POSTS
Yes the catalytic converter was replaced from another Dodge Omni, but it was a different catalytic converter. It wasn't the same size. Would you reccommend I get a different catalytic converter and replace the O2 sensor?
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Sunday, May 4th, 2008 AT 1:00 AM
Tiny
LEGITIMATE007
  • MECHANIC
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The two or three times that the o2 sensor failed, were they all stuck in a rich position?
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Sunday, May 4th, 2008 AT 11:20 AM
Tiny
LEGITIMATE007
  • MECHANIC
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I'm trying to get the correct diagnosis on this, I don't wanna just start you spending on parts and none of them are fixing the problem here, so forgive me if It seems like im beating around the bush a little.
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Sunday, May 4th, 2008 AT 11:21 AM
Tiny
KATI
  • MEMBER
  • 6 POSTS
I'm not 100% sure about that. I just rely on what my computer fault codes tell me and sometimes it's lean or rich. I got lean this time. These are actually the codes I got last time I checked:
12-battery disconnected recently
32-computer didn't see change in air/'fuel ratio when EGR activated - check valve, vacuum lines, and EGR electrical
11-No ignition reference signal detected during cranking (bad Hall effect)
OR timing belt skipped one or more teeth;
OR loss of either camshaft or crankshaft position sensor
51-Oxygen sensor stuck at lean position
55-end of course.

So.I'm putting in a used O2 sensor today to see what happens because I don't want to put it a new one until I know what's going on. Thanks for helping me though, my dad's a mechanic of 40+ years and he doesn't know what it is either.
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Sunday, May 4th, 2008 AT 1:21 PM
Tiny
KATI
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I forgot to mention that I took it to DEQ and it failed with the HC at 1329 and the CO at 9.79. Don't know if that helps.
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Sunday, May 4th, 2008 AT 1:26 PM
Tiny
LEGITIMATE007
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There are several things wrong, obviously but Im gonna say lets start with the egr valve. Check all connections and make sure the vacuum line is connected and that it doesn't have any cracks in the hose, have it tested too. The plug and the egr itself, its probably stuck closed.
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Sunday, May 4th, 2008 AT 10:53 PM

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