Check Engine light on

I've got a check engine light on, came on Sunday morning. Code is P0455 - Evaporative Emission Control System Leak Detected (gross leak). Gas cap is on tight. I'm thinking something got knocked loose while wheeling on Saturday. Guess I'll have to drop the tank this weekend to see what's up.

That sucks Do you have tank armer?

mumblewood wrote:That sucks Do you have tank armer?

Just the stock skid plate that I've raised 1.5". There are no new dents in the skid plate. Since I've raised it, I don't hit it very often.

I had the exact same code about 2 years ago. I checked every gas line, fitting, and anything else connected. Bought a new gas cap, no luck. My check engine light was on for 2 years! It was also hard to start like it needed to re-pump fuel from the tank to the engine. One day, the check engine light was gone, and my jeep starts no problem now! My conclusion was that it must have been a check valve on the tank that was stuck open so that when the engine turned off, pressure was lost and the fuel was draining back into the tank. I remember reading someone elses post where they had the same problem. I'm pretty sure the check valve was jarred loose when I went over a ledge and slammed my gas tank skid on a rock.

Well, I've got about 18 months to my next emissions inspection, so if I can't find anything, I'll probably just run it with the light on for a while and see what happens.

The best way to find out is to take it to the dealer and have them do a smoke test. They pressurized your fuel system with smoke, and look for the leak. Not sure on the price though.

I'm wondering if I raised my skid plate too much, to the point where something is being pinched, or rubbing to the point where it got a hole in it. That's why I'm thinking I probably need to drop the tank just to check it out. It's pretty tight to the tub where I've got it right now. If that's the problem, it won't be too hard to drop the tank back down 1/2" or so...

Bad thing is, if its just a plastic fitting or section of hose, you have to buy the entire hose assembly. I had to do it.

If it's just hose, you can buy fuel system hose from the auto parts store, and cut to fit, but fittings are a different story...

So I think I figured the problem out. I think when we were at the Chevron station before our wheeling trip on the 22nd, I overfilled the gas tank. Then heading straight offroad, that allowed gas in the filler tube to overflow into the vent lines. It took about a week for that overflow to all evaporate (I could smell gas around the filler cap area up until a couple of days ago). On Saturday I disconnected the battery for a bit, and then reconnected. I've been through 6 or 7 complete warm-up cycles since then, and no codes.

Hopefully that's all it was...

I hope you're right, but disconnecting the battery got rid of the check engine on mine also, but would come back on after a couple weeks.

Light came back on yesterday

I really don't want to drop the gas tank...

Might be time for a smoke test. Is your jeep still under warranty?

It's kinda under warranty, it has the 7/70 powertrain warranty (I'm at 56K miles), but I'm not sure if the fuel system is covered by that.

I have so many mods that could be blamed for this, that I don't really want to take it to the dealer (body lift, motor mount lift, gas tank skid modifications, cold air intake).

Found the problem today while underneath the Jeep installing the rear control arms. One of the plastic clips that holds the evap line on was broken.

Why was it broken?

Because the FT 3" Trackbar relocation bracket sticks up too far and hits it at full suspension compression.



All of the pieces were there, so I used 3 zip ties to tie the two halves of the clip back together. Not sure if it is airtight though. Unplugged the battery, so the light is out now, we'll see if it comes back on.

I am not very impressed with the design of that trackbar relocation bracket. It sticks up way too far for the amount of lift and bumpstop extension. In addition to breaking that clip, it also is rubbing on the two rubber hoses that go from up above the gas tank to the rear axle (vent tube), and has nearly rubbed a hole through one of them...