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Q: Engine light keeps turning on, 2006 Dodge Caravan

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Purchased vehicle 9-30-2016. On my way home the engine light came on. Took to o riellys and they're obd scanner came up with the code p0456. So we replaced gas cap disconnected battery. Four days later light back on. Had scanner 're read and got p0456 again,and code p0302. Took to dealership Friday 10-21. Told problems had been fixed. Light came on today 10-22. Got computer scanned again and both codes reappeared!! I need to know please if this is because the dealer didn't erase codes,or,if problems weren't actually fixed?? Asked for print out of what was done before I left dealership and I was told there isn't one because I'm not paying for service???Asked for one anyway for my records and was told to come back Monday to get one?? Please give me your advice. Thanks so much for your time. Kimmie

My car has 10000 miles.
My car has an automatic transmission.

A: It sounds to me like the dealership simply ...

It sounds to me like the dealership simply tightened the gas cap and didn’t charge you for it nor recorded the transaction. Not to worry though. I don’t believe tightening the gas cap would be the proper repair. What you have are 2 codes: a P0456 for an evaporative emissions leak and a P0302 for a cylinder 2 misfire. Could these be related? Not likely. The evaporative emissions code needs to have the system properly tested for the small leak as indicated by the code. A leak in the system could be anywhere from the gas cap to the tank to the engine. The misfire code could be caused by a few things; spark plug, ignition coil, wire harness, injector, ECU, intake leak at cylinder 2, etc. A quick test that you can do is swap the ignition coil with another and see if the code changes cylinders. If it does, the coil is faulty; however, as stated earlier, there are a variety of things that could be the cause. Without seeing data on a professional scan toll, the source can be difficult to pinpoint. The scan tool does not diagnose. It leads the technician to the system that has the fault; the computer does not know what the fault is, only that it is not operating properly. YourMechanic has several technicians available that can assist you with a check engine light inspection and provide an estimate and direction of repair.

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