Holy crap those things are pricey. I want to make sure that its the problem before dropping the dough. 95 Merc Tracer 1.9L got a 157 code and a 214 code. MAF sensor voltage low and cylinder ID circuit faulty. The thing is very hard starting and idles a bit rough. Might be some power loss too, but I wouldn't know, its not my car. Any help is appreciated.

They should cost under $100. They are VERY durable, so if you can get one cheaper from a recycler, do it.

You can't just check resistance or anything really, they can be cleaned though, and when they get dirty the engines run very lean (buck, no power etc).

well, is what i did. Get a vacume tester, one which you can pump and create vacume. Now do down to autozone or a local shop, have them connect their computer to it. Take out your MAF sensor and create a vacume in the end, look at the gauge on the vaume tester and the number on the computer and see if they are one in the same.

sorry, dumb answer, thought i saw map sensor. If they are bad not really, those little wires break or just go bad, new sensor.