This is a common problem on the 2.4, the cam position actuator solenoids fail. Had to replace both the intake and exhaust on the wife's 2013 Equinox. Supposedly, the replacements have been redesigned to be more reliable. They are pretty easy to replace. They are underneath the plastic covers, and are close the the crank pulley end of the engine. The P0013 points to the exhaust side (intake and exhaust use different solenoids), and the exhaust is towards the rear. Loosen the hose clamp under the air intake resonator, and it just pulls off. Remove the oil filler cap, and pull the plastic cover off. Unlock the electrical connector, unplug it, and there's one bolt holding the solenoid in place. They just slide out, but get ready to catch some oil drips. I found the replacements on Amazon for about $30 apiece. Smear a little oil on the O-rings, slide it in, tighten the bolt, plug it back in, and replace the covers. There are helpful Youtube videos showing how to do these too.