So on my drive home today, I got a check engine light. Upon scanning it, the code came out to be P0503. Based on what I have seen this is the "vehicle speed sensor circuit erratic. Which sensor is this, and where do I find it (both on the car and what do I order?) The car is an 06. Thank you for your help in advance.
Luis

 

Just because a code says speed sensor, it does not mean the sensor is bad. If yours was bad it would be extremely rare.

I'd start by checking the ground wire on the back of the cylinder head, since this ground is directly responsible for VSS function.

 

OK, so let me update...
Today on the way to work, the VSA light was still on, on the way home from work, I stopped by O'Rielys, and the VSA light did not come on... when they checked the code, I was showing misfires, and no VSA code. After explaining to them that the car did not run like all 4 cyl were misfiring I had them clear the code to see what happened and the car has no codes now. Not sure what was going on but I will keep you guys updated.

I didn't see any ground behind the head, and nothing looked broken or out of place.

Thanks again.
Luis

 

I assure you the ground is there and it's not easy to get to.