My 96 Jetta 2l has OBD2 codes 102 and 510. checking the Chilton manual (pretty useless most of the time) instructions to check the air flow sensor says that resistance between terminals 1 and 2 should be >4000 ohms, it measures about 47k ohms and that terminals 2-3 should be less than 1000 ohms and this is in the 57k ohm Manual also states resistance between 2-3 should change when move teh "plate up and down" inside the sensor ( BOSCH) . I see no plate but a ceramic substrate board with metallic silk screened traces on it. Manual also states harness voltage should be 4.5-5.5 V on terminal 2-3. i get 15 mv or so.

according to the manual the sensor is bad yet the harness voltage is basically nill unless the manual is wrong as it indeed seems wrong about the sensor plate that is moveable.

Code 102 is thrown immediatly Code 510 seems to take some driving or maybe a restart of the engine to appear. Manual also states that there are two throttle position switches to locate one for closed one for full and to test contunity of both. There is only one with one wire harness. I do find a pair of sensor pins that continuity testing shows a switch opening and closing at throttle close position ( I forgot which pins sorry)

It seems the mass flow sensor is kaput but I do not have conficence given the manual test procedures and inconsistancy and do not want to just replace a rather expensive part if not the problem. I would appreciate any ideas or help you can offer.

Thank you
don

Get some carb cleaner and clean your MAF sensor, your idle control valve, and your throttle body. You probably don't need any parts.