[OregonUSA52LV8]

8/5/12

So, my jeep is throwing a check engine light but the only problem is that every time I hook it up to a reader it wont communicate with it. So, I'm left with guessing. I've owned my 5.2L V8 Jeep Grand Cherokee Laredo for 5 years now. It has 175,000 miles on her and it usually throws the check engine light when its hot out/ when I'm driving it a lot. It does run bad occasionally as well (minor jolting here and there, hesitation here and there, very low idle here and there ext.) Here is the list of items I have replaced over the years: Ignition, ignition coil, fuel filter, air filter, oil changed regularly, coolant flushed, all fluids level, spark plugs, spark plug wires, cap and rotor, PCV valve, cleaned the throttle body out nice and good with throttle body cleaner, used fuel injector cleaner multiple times, there are no intake / vacume air leaks that I have noticed at all either. I have never replaced the o2 sensor though.. and I'm getting 280 miles a tank in city. not sure if that's normal; use regular gas. Does not smoke at all. I'm fine with replacing a few things that are common culprits. any one experience these same problems and fixed the problem? thanks in advance!


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SOLVED: 8/8/12

So I wanted to check back to report on the oxygen sensor. I ended up replacing the o2sensor, sparkplugs, oil breather element, TB sensor, Idle Control Valve, and the air temp / pressure sensor (all totaled ruffly $150 installing it myself) and as im sure you all know the oxygen sensor is a complete btch to change. the wire is located up WAY TO HIGH and im sure there is some unique tool dealers use to replace them (I used my wife's chicken tongs to pull it down and hold it steady while I pushed up the connector with an extension zip tied to it ; ) ) it was hard core, but did the job after many tries at it... Although I now hate Chrysler...lol Anyhow I got it done before I had to work today though. Fixed the problem. No more codes and she runs perfect now!

[ZeeJay1997]

if you could get the code, it would probably confirm that you need to get you some new Mopar or NTK o2 sensors. Pull the code to be sure.

[JustN11]

FWIW, my 4.0 gets 380 miles on a full tank in the city. Your 5.2 will be less, but not that much less. Which makes me think that it might be O2 sensors. Also, I know you cleaned the throttle body, but did you clean the IAC as well?

[ZeeJay1997]

OP, check to see it there is 12v anywhere on the data link connector with key on. I know the 97 data connector is on the same circuit as the cig lighter. Reading the code is going to be key here. maybe someone will look up the pin number for you. Also get under the vehicle and do a thorough inspection of the O2 sensor wiring, especially around the moving parts.

JustN11 - The reason I suspect the O2 sensoe is because of the symptoms he listed (heat related) and the fact that he does not know the condition of the sensors.

[JustN11]

ZeeJay- that's true. After 175k miles, it's a good bet that at least one of them is shot. Between the heat and abnormal (as far as I can tell, but I don't drive a v8 and don't know his driving style) fuel consumption, I think it would be plenty safe to replace both sensors and see if that doesn't help out at all..

[OregonUSA52LV8]

Originally Posted by JustN11

FWIW, my 4.0 gets 380 miles on a full tank in the city. Your 5.2 will be less, but not that much less. Which makes me think that it might be O2 sensors. Also, I know you cleaned the throttle body, but did you clean the IAC as well?

I think I may have. I removed the sensor behind the throttle body attached by two hex screws (is that the IAC?) and soaked it in a solution and then put it back on. It wasnt very dirty though in the first place though and it did not help the problems. It was only $25 at the auto parts store new though maybe I should just replace that while I'm replacing the O2 sensors as well?

[OregonUSA52LV8]

K, so have read on the boards about replacing the TPS, the IAC, and O2 Sensors sensors so far. Since I have a lot of miles and they have never been replaced anyhow I figure I should add these to the list of what Ive replaced and hope for the best (a couple of them are cheap anyhow). Now, what brands should I go with? I've heard NTK or Mopar O2 sensors for the O2 sensors (Dont know which is better though?) what brands for the other sensors you think? thanks again!

[PolkaPower]

Just use Mopar parts for the other sensors. Nick can get them for you with a discount. kolak@aol.com Email him and tell him what you need.

[HighLonesome]

You can get the codes by turning the ignition on and off 3 times. The check engine light will flash the codes.

[OregonUSA52LV8]

Originally Posted by HighLonesome

You can get the codes by turning the ignition on and off 3 times. The check engine light will flash the codes.

Thanks, yea I just found this page today:

http://www.jeepforum.com/forum/f12/h...codes-1257145/


I'm going to try to do this today. ill check back later today. thanks everyone

[OregonUSA52LV8]

Originally Posted by OregonUSA52LV8

Thanks, yea I just found this page today:

http://www.jeepforum.com/forum/f12/h...codes-1257145/


I'm going to try to do this today. ill check back later today. thanks everyone

SO, ran the CEL diagnosis and it was super easy. Here are the results:

Code 12: from cleaning my battery terminals under 50 starts ago. Check.

Code 21: Oxygen Sensor or Circuit:

and finally

Code 52: Oxygen Sensor - rich condition indicated


So I should probably go ahead and replace oxygen sensors then I suppose : )


But just to make sure what is up with the code 52? or is it typical to get a 21 and 51 or 52 when a oxygen sensor goes bad?

[HighLonesome]

There is only one 02 sensor.

[OregonUSA52LV8]

ah, im getting mixed reports on this fact. every auto parts store and mechanic i call say there are two oxygen sensors (one upstream and one downstream) but yea I've only ever owned cars with one so....?

[HighLonesome]

I'm right, they are wrong.

[PolkaPower]

How about you go and look. You only have one though.