The Infamous code 51????? -
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post #1 of 6 Old 01-17-2010, 03:47 PM Thread Starter
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1997 TJ Wrangler 
Join Date: May 2008
Location: pa
Posts: 11
The Infamous code 51?????

ok guys, finally got my jeep running again since my last post a couple of days ago. Everything i thought was fine, but now i have the infamous code 51. I know what most of you will reply so save the o2 sensor speech. Here is what i did so far:

replaced BOTH O2 Sensors about 5 times
replaced MAP sensor
replaced exaust manifold
replaced cat
cleaned throttle body
new spark plugs
new rotor
new cap
new wires

Next i think im going to check for vac leaks, any other ideas????
Gas Cap? Gas tank bleeder valve? i'm almost ready to sell the damn thing.

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post #2 of 6 Old 01-17-2010, 05:50 PM
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2000 XJ Cherokee 
Join Date: Apr 2002
Location: out in the garage - Minneapolis
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You have OBD-II, right ? Why not stop by the auto parts store and borrow their Check Engine Light trouble code reader and download the codes ? Pxxx OBD-II codes are much more specific about the malfunctions than the generic codes like 51, and will help you focus your troubleshooting.

Have you inspected the wire harness and wire plugs for your O2 sensors. If you have a good O2 sensor but bad O2 sensor wires, the ECM can't tell the difference. Look for broken wires, chafed or burned wire insulation, and short circuits.


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Last edited by CJ7-Tim; 01-17-2010 at 07:18 PM.
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post #3 of 6 Old 01-17-2010, 05:55 PM
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1997 TJ Wrangler 
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No, he has obd, not obd II
His is 97, we don't get that luxury :P

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post #4 of 6 Old 01-17-2010, 05:58 PM
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Originally Posted by finalreckoning View Post
No, he has obd, not obd II
His is 97, we don't get that luxury :P
IIRC all 1996 vehicals and up have OBDII?...
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post #5 of 6 Old 01-17-2010, 06:33 PM
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2009 JK Wrangler 
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Yes 97's have OBDII they just use the older number system instead of the newer "PO" style. is the code causing it to run bad after fixing all those issues?
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post #6 of 6 Old 01-17-2010, 07:29 PM
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Originally Posted by finalreckoning View Post
No, he has obd, not obd II
His is 97, we don't get that luxury :P
wait a sec. I have a 97 TJ and mine is obd2
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