I have a 2001 4.0 5spd auto 4x4. I am having trouble with the check gas cap light. I have replaced the gas cap and reset the ecu. It stayed off for several weeks and is now back on. I have read the TSB for this. What have other people done to fix this?

 

Has nobody had this problem?

 

The dealer has a special tester that will help locate the leak. The OBDII diagnostics are capable of detecting a vapor leak that is the equivalent of a 0.020" hole. The fuel cap light is for larger leaks but you still may not be able to find it. I would start with a general inspection of the filler hose and clamps and the hoses to the charcoal canister. If you can't find it, you may have no choice but to have the dealer diagnose it.

 

I had the codes ran last night. It is showing P0457 only. I looked a little bit last night just around the service port area. I was surprised to find no clamps securing the lines. I will check the other areas tonight. I want to check everything I can before I pay somebody.

 

I am having the check fuel cap light that eventually flags the CEL. So far I have replaced with aftermarket fuel cap and reset and lasted 3 week before flagging again. Replaced the aftermarket cap with with a new Ford fuel cap and reset and lasted for a week and then flagged the check fuel cap again. I finally broke down and had the dealer try and diagnose the problem.

They first replaced a solenoid assembly, part number YL5Z*9F945*AA. Where is this part located? I can not spot any new parts under the hood. They said that replacing that did not fix it. They then suggested replacing the valve assembly, Ford part # F87Z*9C915*BA. They did not have enough time to get the second part installed, so I took the part with me and installed it tonight and that is when I noticed I did not see any other new parts under the hood. The only thing I found under the hood was a test lead that they left behind.

From what I understand from the TSB, only 2 parts are used in this fix and I have now replaced both. Now it would be down to a leak in the line somewhere.

 

I haven't seen a TSB on this but it may exist. YL5Z*9F945*AA is a "canister solenoid" so that explains why you didn't see it under the hood - the canister is under the bed ahead of the spare tire.

The leak could be anywhere in the the fuel tank, the valves or the hoses connected to it. The two valves that control flow into and out of the system are the Canister Vent Solenoid (near the canister) and the Evaporative Emissions Canister Purge Valve (in the engine compartment). Other than that, you are stuck looking for a leak, possibly quite small.

As i mentioned in my other post, the Ford dealer should have a Rotunda tester that will help them find the leak.

 

They said they had to replace the one part in the rear that you describe and that did not fix it so I replaced the part in the front that they replaced. Now I can go and look and see if they actually replaced it. On Monday I am going to take it back so they can finish the 95.00 diaganotic test.

 

I took the truck back this morning and had it retested. I was told everything is good now. This weekend I am replacing the 2 precat O2 sensors and cleaning the maf in search of some gas mileage. Hopefully with everything I will easily be back in the 300 per tank range.