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Discussion Starter · #1 ·
1995 Wrangler Sahara, 200k miles

I had a hole in my exhaust just in front of the muffler. I ran it with the hole until the pipe finally broke free of the muffler. Not long after it broke free my "check engine" light came on. As soon as the engine is turned off the light goes out, but now comes back on after the engine warms up.

I installed a new cat converter & muffler. (nothing special, just one of those universal jobs) It sounds TONS better than it did before, but the check engine light came back on again.

I'm the original owner of this Jeep, the converter was the original, the muffler was the 2nd one.

Is there a reset?
 

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Take the ground off of the battery for like 20 min. It should clean up codes. But if it comes back on you'll have to find the number do deal with the issue. There is a tread some where here with instructions on how to read codes.
 

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Find the codes by turning your key to the on position (without starting it) and then off again three times on the third time leave in the on position and your codes will be blinked out via the check engine light.
I w0uld bet you get a 21 as well of course the 55 signaling the end of the codes
so for example the 21 will be a flash-flash-pause-flash
 

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Post the codes you get I have a master list hard copy here by the computer (with many codes that arnt on some of the threads I have seen) and I will reference them for you if you are unable to find them...
 

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Discussion Starter · #6 ·
It's more difficult to read those flashes than I thought. I def get the 55 at the end. I'm pretty sure that I'm getting a 21 code at the beginning.

Does any of the codes seem to jive with the issue of my tailpipe breaking free? The light came on right after that.
 

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21 is an O2 sensor not sure in the YJs but TJs have two and it seems like its always the one near the engine although mine was the downstream one after the cat
 

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My YJ only has one O2 sensor. Reading the codes are a little tricky you need to do them a couple different times in a row to make sure you are getting the correct code count.
 

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Help, I'm a girl

My 1995 Jeep Wrangler is flashing the check Engine light at me. I followed the instructions and got:

3 4 5 5

I know the last two fives signal the end. What do the first three numbers mean? Any help is much appreciated.
 

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You may have a "hard code" stored in the computer. It probably triggered when the muffler came apart. After fixing, it may not clear itself. You may have to find someone with an OBD 1 (OBD2 was 96 and up I believe) scan tool that can erase it. After that, if it comes back, you may look into replacing the o2 sensor as recommended.
 

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I couldn't remember if YJs had cruise from the factory or not.

My Islander has factory AC.
 

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Muffler wouldn't throw CEL. The only thing on the exhaust system that throws CEL is O2 sensor and for the yj's they are fairly cheap compared to other cars. I replaced mine when I replaced the exhaust.
 

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I am having the same problem with the trouble codes. My Jeep was running a little rough on take off, the rpms would drop and it threw a code saying it was the throttle positioning sensor. I changed the TPS and it is still doing the same thing and throwing same code. I am determined to do all the work by myself on my new found obsession. Yes, I am a girl too so I would love all the suggestions I can get.
 

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I am having the same problem with the trouble codes. My Jeep was running a little rough on take off, the rpms would drop and it threw a code saying it was the throttle positioning sensor. I changed the TPS and it is still doing the same thing and throwing same code. I am determined to do all the work by myself on my new found obsession. Yes, I am a girl too so I would love all the suggestions I can get.
How does the lead connecting to the sensor look? The contact inside of the opening could be fouled. And btw I love hearing about a woman doing her own auto work, bad ass!
 

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Any code is what the computer thinks is the problem, if you get a code for the TPS or O2 sensors, remember, the sensor itself is only one part of the circuit, you also have to make sure the wires to the computer are ok, all the connectors, and the computer itself....

Also, an O2 sensor code does not necessarily mean the O2 sensor is bad, it could be a vacuum leak causing the O2 to read lean, or a leaking fuel injector can cause a rich reading, both can throw and O2 code because the O2 reading does not change.

Other sensors can be affected by the supply voltage being low, if a TPS has a low input voltage, it cant send the correct signal back to the computer. The Computer sees a low TPS/IAT/MAP/ signal and can set a code for any of those all of those or none but have a drivability issue.
Grounds can also cause issues, a poor ground can cause a high reading.

Do you guys have a volt-ohm meter? even a cheap one can work.
 
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