I have a '06 Ram 1500 with a 4.7L. A couple months ago the check engine light would come on at half tank. I did this for about a month or two then quit. It has been about two months since the last light and it came on last night at half tank. It seems to be weather based. Am I making excusses or is this a valid reason?

 

Next time it comes on take it to autozone or somewhere and have them pull the code.

 

Did you try the key trick to see if there's still any codes the computer is holding?

 

Probably throwing an evap code. Once enough air fills the tank, it may be exposing a small leak. Could just be bad seal on your gas cap. Check the gas cap o-ring for cracks, replace if necessary. Get the code checked at an auto parts store next time the CEL comes on. Also, be sure you are tightening the gas cap well when you fill up. Give it a twist and let it click several times.

I have a recurring issue on my wife's Jeep with this. Even took it to dealer and had the evap system smoke tested and supposedly fixed. But we've had it again since taking it to the dealer. It does seem to occur after burning off some gas after fillup. As far as weather goes, we've had it happen in southern 90+ degree summer heat and in the winter, so not sure that's related at all.

Check the code next time it comes on and don't assume this is your problem.

 

Thanks ya'll. I did have them pull the codes and they did say gas cap. I changed it now it's back. I read somewhere that it may be the EGR valve. Any opinions on that?

 

what exactly was the code ?

i dont know how many times ive been to a parts store for them to read a code from a friend or family members vehicle and 4 out of 5 times they say bad gas cap. and none of those times has their gas cap been bad.

 

Gas cap is always the first thing they say when you get an evap related code because it's a common mistake people make, leaving the gas cap too loose when they fill up with fuel. It's the easiest and first thing you might as well check. As I said, I took my wife's Jeep to the dealer and had them test the system and they supposedly found a problem and fixed it but we've had the light come on with the same code since then. I've never had my truck throw a code for anything but the EGR valve, and it's a different sensor, different set of codes, by the way for the OP's question. And I did have to change it after I reset the first code only to have it come back a week later.

You can take it in and they have a test they can run to see what the problem is. I paid a couple hundred bucks for my Jeep when all was said and done but, frankly, I don't know how much of that was for the test and how much was for the part they replaced and the labor to go with that.

Get them to give you the actual code and look it up online. When I get Advance Auto to scan the code on my wife's Jeep, before I found out I can make it display in the dash, they always tell me it's a generic evap code and they have no idea what the exact cause is. You have to take it from there yourself or take it to a mechanic.