My check engine light went on in my 2004 jeep wrangler, I looked up the code, PO456, it said very small leak has been detected in the evaporative system. I changed the gas cap and the light still came on. This has been a problem for a while, it goes away for a while and then it comes back on a few days or even weeks later.............help
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codse p0456 refers to evaporative emission system-- very small leak detected.. probable causes -----mechanical fault---hose connections loose---EVAP pressure sensor.. I would look at the EVAP sensor as being faulty
Usually this P0456 code is caused by an incorrect or faulty gas cap. Filling the fuel tank with the engine running could conceivable cause this code as well or if the cap wasn't properly tightened. Any of the following could also be the cause:
* A small leak in any of the EVAP hoses or fuel tank hoses * A small leak in the purge valve or vent valve * The EVAP Canister may be leaking
p0456 is ayoun evap fault honestly this is a job for a professional with the correct diagnostic equipment jsut from memory it is a vent control fault. if you have access to alldata or mitchel on demand you can get diagnostic steps for the proper diagnosis. unless you have the proper tools this is a job left to a good repair technician that you trust sorry i cant give you a straight answer but you will throw away money buy just replacing parts and hoping it fixes it, just food for thought if the code is cleared it will take time to come back the only way to conferm the repair is a evap self test that can be done with the adiquite scan tool
YES A CAP FROM THE DEALER WILL MOST LIKELY SOLVE THIS ISSUE...SOME OF THE AFTERMARKET CAPS ARE NOT MADE TO THE PROPER SPECS TO MAINTAIN PROPER PRESSURE/VACUUM ON THE SYSTEM WHEN THE EVAP TEST BY THE COMPUTER OCCURS
Your vehicle’s computer system has self-testing capability. When the computer senses that there is a problem with some of the components it stores the correspondent trouble code(s) in its memory and lights up the "Check Engine" or "Service Engine Soon" light to tell you that there is a problem and you will need to have the car diagnosed and repaired. The only thing you could do is check the gas cap to make sure it's tight. A loose cap causes a fuel vapor leak and that will turn the light on. If the cap was loose it may go off after a few drive cycles, if not you will have to have it checked.