Vehcile speed sensor
 

New to the Volkswagen forum, tried searches for info, I'll try a post now. Just bought my son a 96 Jetta Trek, 2.0 manual tranny. previous owner had just installed a clutch and veh speed sensor (so she says). Supposedly a couple people used OBDs during their look over of the car but declined buying. When I bought it it ran great and no service engine light lit. Got a temp reg (in CT you need emission check before final reg) put a muffler on it a couple days ago, ready to take it to a emissions station today and he comes home from school and the engine light is lit. Checked it at Advance Auto and it reads PO501 Vehicle Speed Sensor A Range/Performance, then 2 pending codes, PO172 System too Rich (Bank1) and PO103 MAF or VAF A Circuit High Input . Wouldn't be too bad if I just needed a new Speed Sensor ($30 bucks or so??) But a Mass Air FLow looks to be about $150!!. Could the pending codes be related to the speed sensor? Also being new to the Volkswagen scene, where is the speed sensor and is it easy to replace? Any help would be great!

Car is heating up for sure. Check the Radiator and make sure the water and the coolant is passing through the pipes without any leaks that way it cools the engine.