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-   -   Decoding Check Engine Light (http://www.wranglerforum.com/f282/decoding-check-engine-light-71087.html)

Gumpy2030 12-04-2010 07:35 PM

Decoding Check Engine Light
 
My check engine light came on today. Is there a way to read what that code is telling me to do without taking it to a shop? I know on older trucks I have had you can turn the keys a few times and then count the amount of times the check engine light flashed. Then the number of flashes correlated to a distinct code I was able to find on the internet or a chilton manual.

6InARowMakesItGo 12-04-2010 08:15 PM

ive seen a way to do it like you described but ive never been able to get mine to do it. ghetto zone will do it for free.

06TJfototkr 12-04-2010 08:15 PM

Put the key in, then turn it to ON (the spot it goes to right before you start the Jeep), and then turn it a click back. Do that 3 times (ON, OFF, ON, OFF, ON) and if you did it right you should see the codes pop up where the mileage usually is, then it will say "done."

On older TJs, a light would flash a few times. Luckily on 04-06s (maybe 03s?) it reads the actual P0xxx codes.

Robinh57 12-04-2010 08:58 PM

Go to autozone. They will code you for free.

Gumpy2030 12-04-2010 09:55 PM

Quote:

Originally Posted by 06TJfototkr (Post 908307)
Put the key in, then turn it to ON (the spot it goes to right before you start the Jeep), and then turn it a click back. Do that 3 times (ON, OFF, ON, OFF, ON) and if you did it right you should see the codes pop up where the mileage usually is, then it will say "done."

On older TJs, a light would flash a few times. Luckily on 04-06s (maybe 03s?) it reads the actual P0xxx codes.

Thanks that process worked perfect. I get the code P-0455 which from other posts appears to be the following.

"This indicates a fuel vapor leak or lack of purge flow in the EVAP control system. It means a large leak has been detected."

I will do some reading up and see if I can't figure out what has caused this. Hopefully just my gas cap but I am not usually that lucky.

JDsDream 12-04-2010 10:36 PM

I copied this from another site. Hope it helps.

P0455 is a large leak in the evaporative emissions system. This is the system that stores fuel vapors and burns them in the engine. A large leak sounds like it may be easy to find, but it can be as small as a .040" crack in a hose. Start at the gas cap. Make sure it's tight, make sure the seal is ok, make sure the check valve in the center shows no signs of corrosion or rust. If it does, replace it.



If the cap looks ok you would need to slide under and start checking lines underneath. From the filler neck to the tank, and then the evaporative emissions lines from the tank up to the engine compartment. In the left front corner of the engine compartment you will find where the lines all end up. The leak detection pump, the charcoal canister, and the purge solenoid are all up there. Check all lines for any cracks or holes. If you don't find anything you can also check the purge solenoid for leakage with a hand held vacuum pump.



If you just can't find the leak you can take it to a shop. They will have a special machine for finding these hard to find leaks. It hooks into the system and pressurizes it with smoke, and you find the leak by finding the source of the leaking smoke.

s3nt3nc3d 12-05-2010 01:20 AM

In MOST cases, a large evap leak is caused by a faulty or loose gas cap. Definitely try that first.

JD Adams 12-05-2010 02:46 PM

I agree; most 455's involve a loose fuel cap. If it's an aftermarket cap, check that the internal valve has not failed and that the seals are good.

Gumpy2030 12-06-2010 06:33 PM

Is there a way to test and see if the gas cap is bad without just replacing it? I did a quick visual on it and the seal looks fine.

OsageJeep 01-31-2011 08:10 PM

My light just came on tonight as well and I got the P0455 code too...anymore info?

jasonwrangler 01-31-2011 08:27 PM

Quote:

Originally Posted by Gumpy2030 (Post 911099)
Is there a way to test and see if the gas cap is bad without just replacing it? I did a quick visual on it and the seal looks fine.

just get a new one. its 5 bucks.

wanderer1951 02-01-2011 10:42 AM

take the cap off, then put it back on . Light should go out after a bit. Ive had it happen a few times,

Gumpy2030 03-02-2011 09:45 PM

Well I have been fighting this code forever. I replaced the gas cap about a month ago and reset the codes by unhooking the battery. The P0455 code comes right back and wont go away. I guess it is time to start following the lines and figuring out where this stupid leak is. Hard to sell a Jeep when your check engine light is on. :)

Hardermods 03-02-2011 10:22 PM

Check all the hoses around your charcoal canister. Chrysler hoses at the 90 degree bends tend to crack or come loose and fall off

http://www.nakedjeep.com/Projects/EVAP/Pix/EVAP01.jpg

john97TJ 03-02-2011 10:43 PM

Quote:

Originally Posted by jasonwrangler (Post 1026203)
just get a new one. its 5 bucks.

I've bought 5, not because of codes, but because I keep leaving the cap on the top of my Jeep and then driving away.:banghead:

jkaufman_95 03-02-2011 11:03 PM

Quote:

Originally Posted by john97TJ

I've bought 5, not because of codes, but because I keep leaving the cap on the top of my Jeep and then driving away.:banghead:

I did that. With a bus. But I left the fleet fuel card on top of the pump with it. Oops. Oh yeah where was the pin? Written on the card.

Gumpy2030 03-09-2011 06:29 PM

So I have checked all my hoses and even pulled the gas filler neck out to make sure there is nothing wrong there. I can't find anything visually wrong. I guess I am having the local shop run a smoke test on it tomorrow and see what they find. He said it may be a bad solenoid which would run about $150 to change. That sounds really high but I have no idea. I am running out of time because I have a guy wanting to buy it now and we are just waiting on getting this code fixed.

Gumpy2030 03-09-2011 11:46 PM

I came across this video on YouTube that I thought was pretty cool. I wish I could get my hands on one of those smoke machines because I could do that my self and not have to pay the shop $70 bucks just to hook it up plus the cost to fix the hoses. Any one know if you can rent those from Checkers?

http://www.youtube.com/watch?v=yKVq2BjG1X0


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