03 Ranger


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The check engine and gas cap light are on in my ranger and i cant figure out how to fix the problem. I have replaced the gas cap with an OEM gas cap and that hasnt worked. I disconnected the battery and that works for a day or two but thats it. I went to autozone had them re-set it and same thing. The code said something about the evap canister. I have no experience with this so dont really know how to take care of it. Im not one to bring my vehicles to a mechanic to over pay for things I can do so if anyone of you have an idea on how to fix the problem i would like to hear it.

thanks,

Lyle

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That little 50 cent bulb behind the gas cap lamp should have never been put in a vehicle. The light simply means to check the cap. If it is missing or not tightend properly it might be the cause of the check engine light being on. A lot of money has been spent on gas caps when there was nothing wrong with the original cap. You likely have a leak somewhere in the evaporative emission control system. This can be caused by cracked hoses, cracked charcoal cannister or more likely in your truck's case a cannister vent valve stuck in the open position. The system is not fully sealed and when the computer runs a test on the system it sees a leak as the system will not hold a vacuum. Clearing the light will only prolong the agony. When the computer runs the test again the light will come back on.

There are several codes related to the evap. system. Most are in the P0440 to P0450 range. Knowing the exact code will help narrow down the area to start looking for a failure. You may have to resort to taking the truck to a competent repair facility and have a complete diagnosis including a smoke test performed. There are alot of different parts in the system which you can buy and try without replacing the correct part to correct the problem.

If you do plan to get a diagnosis performed DO NOT have the light shut off first. A good technician will use the stored information in the trucks computer to aid in diagnosis. Saving his time can save you money. When the system is cleared of codes this information is lost.

Let us know what you find out.

Lynn

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Could be a number of things, I've seen lots of GM fuel tank pressure sensors go bad and cause evap codes, they will not read and the ECM thinks there's an evap leak. Changed lots of vent solenoids that stick open. Also have changed purge solenoids that will suck vacuum when it's not supposed to.

I'm sure you found the faulty part with proper diagnostics and knowledge of how the system functions. In my world where we work on all domestic brands and a few foreign makes we have to face some challenges which are hard to keep up with. For ex: Ford and GM use vacuum to test the system with the onboard diagnostics. Chrysler on the otherhand uses vacuum only to run a leak detection pump which builds pressure to test the system. These are prone to failure. You have to think backwards in some cases.

This is why I am adamant about finding a shop with the proper people and equipment to diagnose problems on modern vehicles. Just guessing and throwing parts at something doesn't work well for me.

Lynn

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