I have done nothing to the jeep mechanically for a while now. I was driving yesterday and noticed the check engine light came on but my oil pressure, voltage and temp were fine. It came on again 2 times after. I noticed it comes on after about 5 miles and stays on until I turn off the jeep. My oil is a tad low but everything else seems to work fine.

Its a 94 and autozone told me they cant read codes on it for some reason. Does anyone know where I can start to trouble shoot for my problem?

In the past 3 months I have replaced:
Radiator
Alternator
plugs, wires and dist. cap
Radiator Hoses
Oil
Fuel Filter
Air Filter
Muffler and New Cat

All the above changes have been done for atleast a couple months.

 

Go to another shop and get the codes read. Do basic maintenance you listed, along with cleaning the intake and sensors. Not a bad idea to test the sensors while you are at it.

 

seince you have the obd1 system tou need to short it out in the plug witch will cause the engine light to start flashing.i think it is on the left side and the 2 that are top and bottom. it will normall start out by flashing once then twice and it will do it 3 times. that just meant the computer is working then then next time it flashes will be your codes. the flashes will look kinda like this.


- -- - -- - --
this code means 12

this is how i had to test other obd1 systems but i never did it on a jeep.

 

Here is a link on how to get the codes from your 94 (OBDI). Follow this procedure and then post the exact code numbers here for comment.

http://www.go.jeep-xj.info/HowtoECUcodes.htm

 

getting jeep codes is easy, just turn the key on and off 3 times and watch the CEL.

 

The check engine light on an OBDI vehicle has nothing to do with oil pressure or engine temp in most cases. The check engine light is to warn you that there is something emissions related out of spec or an emissions sensor is failing.

 

I tried to read the codes...it doesnt throw any. It just comes on for a second then goes off like normal. The check engine light goes off when you turn it of and wont come back on for about 10 mins or so of driving.

 

then you're doing the procedure wrong. If the CEL lights up, the codes are stored for 50 startup cycles or until the battery is disconnected. It will always show at least a "55" code (end of sequence).


Start with the key in the "off" position
Turn key to "on" (don't start engine)
key "off"
key "on"
key "off"
key "on"

 

Ok so the way you said to do it worked....but my code is weird. I thought it was suppose to repeat it. I have it doing this

* ** ** * then followed by the 5 blinks

 

Looks like its saying battery was disconnected in last 50 key cycles which might have happend.

but 21 says O2 sensor or wiring faulty.

So is this just an 02 sensor issue?

 

12 - battery disconnected (ignore)
21 - Oxygen sensor signal out of range or shorted

Looks like you may need a new o2 sensor my friend.

 

haha I looked online for one and it shows multiple ones for the 94 with 4.0L. All i know is mine isnt in the cat....any input? I can mess with it later tonight if its a burden to ask for advice, Im just at work and was going to order it now from the auto parts so I could install it tonight.

 

what's the difference? i have no idea what store you're looking at.

It's the pre-cat 02 sensor. They shouldn't have another one listed for a 94.

 

That narrows me down to about $83 hahaha. Sucks I just spent $900 the past 2 days on a/c parts, motor mounts, header, and weather stripping

 

WTH? $83 for an o2 sensor? I have no idea where you're looking but here:

http://shop.advanceautoparts.com/web...1444111372____