No need to guess, get an OBDII App and get the codes read and you will know exactly what is going on.
You want OBDFusion, for the iProducts it is $9.99, for Android is is $3.99.
For iProducts you NEED a
Wifi adapter, for Android you can use the Bluetooth adapter.
iProducts adapter -
http://www.amazon.com/dp/B00WPW6BAE/...BWNPO9BZ&psc=1
Android adapter -
http://www.amazon.com/dp/B00WPW6BAE/...BWNPO9BZ&psc=1
So for the basic OBFusion, you are at $30 or less for iProducts and under $20 for Android. Very worth while once you find out what you can do with these Apps.