I took my youngest son to the school bus stop this morning and all was ok, ended up taking my other kids to the dentist and "CHECK ENGINE" light cam on after 1/2 mile from taking off. I pulled over did all the routine checks to make sure I had oil, water, or any other recognizable problems. NONE.
Anyway I have a code reader and I checked it and it came up with code 52 which in my Haynes manual reads>
Code 52-----Oxygen sensor signal input indicates rich fuel/air ratio condition during engine operation.
I tried clearing the code and worked for a minute then came back on of course I knew it would cause I did nothing to correct the problem. My question is "What can be causing the problem?" Any sensors need checking? Looks like if it was any other sensor it would have popped up on reader but have seen times things like that hasn't. Maybe vacuum line?

HELP, I want my Check engine light off. Almost forgot, '94 JGC Limited 5.2L

Nobody have any ideas?!?! Anyway I checked most of the sensors today like TPS, MAP, and Intake Air Temperature I think it is called. TPS is the only one according to Haynes manual was not in the operational limits, it was off by almost a whole volt when the TPS was wide open but tested within the limits when closed. Was going to check the O2 sensor tomorrow if weather holds out and gander at the manual again to see if there may be any others I can check myself easily. On another forum they claim that there is no 52 trouble code for the 94 model and it is my scan tool but I did the old trick of the on-off-on-off(how ever it is supposed to be) deal and it flashed the 12 and then 52 and 55 I think the last was, according to Haynes the 12 and the last number were just the beginning and ending codes and are normal plus with what I read here on the forums they are supposed to be normal.
Also checked what vacuum lines I could and all look ok but tight squeeze in there and hard to get to them all without tearing crap apart.

Are you talking about a 1994 5.2? I have heard that the o2 code can be thrown for many reasons. Fuel pressure, etc. Make sure that is good (change filter?).

I just changed my o2 sensor on my 1994 and I think the code was 27.

OK, in my Haynes manual it definitely said code 52 and with the reader it gave code 52 as well. I also checked using the check engine light and came up with code 52. So it is definitely code 52. A few other people from another forum claims a 94 JGC WILL NOT THOW A TROUBLE CODE OF 52. Anyway, I tested the AMP, TPS, IAC, AND I think that was it doing as the Haynes manual instructed, after doing so of course it prepared me that it would cause trouble codes to appear and it did, I cleared them but the light stayed off for a while and came back on(as I knew it would) with code 52. Today though I took my kids to the bus stop and the check engine light was off. It was raiing outside and was wondering if it is possible that the outside humidity would effect any of the sensors and which one? That is the one I would be thinking was bad. All tested out ok as the manual said EXCEPT the TPS, it was off on the voltage at full throttle by almost a whole volt and thought that might be the problem, but thought it would send it's own code when it was bad. Unless it isn't that bad yet to do so and is just causing another code to appear, can it do that? A buddy of mine said it would be the MAP sensor cause they usually rely on the outside air temperature and humidity to adjust fuel mixture, sounds like he knew what he was talking about BUT I also know he isn't the brightest when it comes to computer controlled vehicles.
Any good ideas people??

Are you saying your 02 sensor is not bad? A vehicle will still run with a bad 02 sensor. If the computer is throwing a code for it then I would replace it. Running on a bad 02 will make your vehicle run rich and will lead to other problems if not fixed.

Code 52 means your engine is running rich, now this could just be a bad )2 sensor or clogged o2 sensor.

The PCM is constantly adjusting your air/fuel ratio whenever it adjusts and the readings from the O2 sensor doesn't change it will set the CHECK ENGINE light telling you something is wrong. the most likely fix is replacing the O2 Sensor.

As for the CE not coming on when you took the kids to the bus stop, it is possible that maybe the engine wasn't running long enough to get up to temperature. The PCM runs in CLOSED loop until the O2 sensor reaches 660 degrees then the PCM uses the readings from the O2 Sensor to adjust air/fuel ratio.

I would change the O2 Sensor.

As for the TPS not getting the correct voltage at WOT - this is normal every TPS I have ever tested, I replaced mine twice because I thought I got a bad one, only read 3.7v at WOT instead of 4.5v which is what the haynes manual calls for.

I took my youngest son to the school bus stop this morning and all was ok, ended up taking my other kids to the dentist and "CHECK ENGINE" light cam on after 1/2 mile from taking off. I pulled over did all the routine checks to make sure I had oil, water, or any other recognizable problems. NONE.
Anyway I have a code reader and I checked it and it came up with code 52 which in my Haynes manual reads>
Code 52-----Oxygen sensor signal input indicates rich fuel/air ratio condition during engine operation.
I tried clearing the code and worked for a minute then came back on of course I knew it would cause I did nothing to correct the problem. My question is "What can be causing the problem?" Any sensors need checking? Looks like if it was any other sensor it would have popped up on reader but have seen times things like that hasn't. Maybe vacuum line?

HELP, I want my Check engine light off. Almost forgot, '94 JGC Limited 5.2L

You can check for vacuum leaks by spraying 2+2 or other carb cleaners around places that have vaccum, intacke manifold, vaccum lines etc. If there is a leak the engine will pick up rpms when it sucks in the 2+2.

If you dont have a vacuum leak and your TPS is out of whack, that needs repalcing anyway, so do it and then clear your codes, ride it again and if the 02 comes back, replace it. I jsut did mine, was shorted and causing alll kinds of drivability issues. My MPG jumped after that to avg 17.5

Also a 94 JGC 5.2L

Alright, it has been a long time since I have been on here with my problem. I still have code 52 showing up. I had replaced the O2 sensor and cleared the code. Ran fine but at the same time I added a bottle of STP fuel injector cleaner. After a short time the CEL came back on and has the same exact code, 52. I had replaced the IAC and TPS as well at the same time I replaced the O2 sensor.
Thing is I have been driving the Jeep and the only real problems I have noticed is it idles poorly and MPG has dropped quite a bit. I was getting and average of 25 MPG and now it is only 21 MPG. Driving habit is still the same as before, not getting any harder on the pedal.
I had done a lot of suggestions to get rid of the problem as well, such as checking for vacuum leaks by spraying carb cleaner around vacuum lines and also using a piece of hose to listen for any leaks. NONE that I can find.
Talking to some other mechanics they claim the fuel pressure would not be the problem cause if so the vehicle would act up at higher speeds as well. IDK just repeating what was said but makes sense to me. I can run 100 MPH down the road with no problems for 46 miles(did that 3 weeks ago when 7 yr old son was flown to trauma hospital). What I have noticed is the Jeep only runs rough when it is warm outside, if temeratures are below 70 I don't get the rough idle as bad and the cooler the outside temperature is it seems to do even better, today with the outside temp being 55 it ran perfect. So, that leads me back to thinking it IS a vacuum line and the outside temperature effects the crack?!?! OR is there a sensor that may be effected by the outside temperature? Maybe the MAP sensor? Although one mechanic said to check that just start the Jeep and then unplug the MAP sensor, if it is good it will cause the engine to die instantly which mine did.
Love the Jeep even with it's minor problems and have great plans for it IF I can ever get the engine squared away. Plans include a lift kit, a little larger tires, and then the major plan of stickign a 5 speed in it. I figure the NV3550 would be a awesome tranny to put in a GC with a 5.2L. I have already added a Magnaflow dual outlet exhaust to give it the appearance of having dual exhaust and it sounds excellent.
Could EGR have anything to do with the way it runs when the outside temperature is low?
Just thoughts running out my brain right now.