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Old 02-28-2012, 10:26 PM   #1
Join Date: Feb 2012
Posts: 5
Check engine

I have a 94 yj it sat for 4 years. Check engine on codes 12,33,21. Did full tuneup, changed o2 sensor still have ck eng. Scanner shows low voltage to o2 sensor, also changed fuel sending unit for leak, does power to o2 sensor come from fuel sending relay?? Also failed emissions co and co2.

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Old 02-28-2012, 10:45 PM   #2
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Location: New River Valley, VA
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Sounds like corroded cabling. That's a bitch to track down, but grab a multimeter and test levels from the o2 sensor back to find where it's giving you trouble.

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Old 02-29-2012, 11:33 PM   #3
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Old 02-29-2012, 11:50 PM   #4
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Location: Michigan
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the Jeep, looking at the wiring diagram, it looks like the O2 sensor get's it's power from the auto shut down relay, not the fuel pump relay (located between the A/C relay and Start relay in the (underhood fuse box). Hope this helps!
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Old 03-01-2012, 12:13 AM   #5
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Thanks will try it
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