My check engine light comes on after about 15min of driving, so I did the error code check from here: http://www.johnr.com/cpucodes.html
and I got codes 13 - Pressure Sensor (intake manifold pressure) fixed at 29.9 inHg and 15 - Oxygen Sensor - Feedback Cancelled
These make sense because my car has headers, so there is no o2 sensor, and the car has an aftermarket intake, which I think might have something to do with pressor sensor error. I'm not sure though.

The CEL was doing this for a while before I bought the car (just a week and a hlaf ago) and I've driven about 200 miles since I got it. 160 of those miles were driving it home after I bought it.

Should i try to get the car to a mechanic as soon as possible, or not worry about it too much?

 

Idle the engine. Go to the pressure sensor and make sure the electrical plug is on. Then pull the vacuum hose off the bottom of the unit. The hose should be pulling vacuum. If not, then find the other end and put that end on a source of vacuum.

IF it is pulling a vacuum and the plug is on the unit, then write down any and all numbers on the pressure sensor and add them to this thread.