Mass Air flow
 

My mass air flow sensor is bad. Can I just replace the sensor or do I replace the whole tube (mass meter)?

The whole thing, probably (as far as I know).

You need to tell what model, year and engine please.

-Tom

Does anyone know why these things fail so much? Do they burn out light light bulbs? I had 2 other cars with the older Bosch "spring loaded door" style (air flow meter) and these lasted the life of the car. The new style with the heated platinum wire is more accurate but do they just fail a lot? Does anyone know how many miles/hours they are likely to last? Should I carry around a spare as has been suggested in another thread? Seems a little crazy.

Thanks,

Mike

Actually,the hot wire air flow sensors "are" just like lightbulbs. With this being said the filiment does eventually burn out. The filiment only gets really hot when the engine is shut off though. Why? The filiment goes through a self cleaning process to burn off any residue it collects while working. I imagine most of them burn out like this, especially if they get too dirty. I refuse to use performance air filters on cars equiped with hot wire air flow sensors for this reason. They are fragile and work best in a very clean airflow.
Adam

Hi Adam,

Good info. When they burn out is the wire visibly broken? What is the symptom of a bad one? Engine won't start at all? Or is there some kind of "limp" mode built in to guess air flow some how?

Mike

Hi Mike,
Yes, the wire should be visibily broken. It's hard too see through the grid but Just use a flashlight. I am 99.9% sure the car will go into a worst case senario limp home mode and it should start. Firts thing I would do is pull the codes and see what your getting.
Adam

As Adam mentioned, don't use K&N type filters with platinum wire MAS units -- if you put enough oil on them to catch the dirt, the oil will get on the wire and cause it to fail, and if you lower the oil enough to keep the wire clean, the dirt coming through will cause the wire to fail.

It heats red hot on shutoff to burn off crud -- it measures airflow by measuring the resistance of the wire with a fixed current. The wire resistance changes with temperature, and the temperature of the wire with fixed current flow is determined by the mass and temperature of the air and air flow rate. Very accurate, but when they get covered with crud, expensive to replace. Buildup on the wire that does not burn or flake off will cause it to get so hot it melts or cracks and breaks.

Peter

Is it only the wire that gets dirty ?
 

I have read about cleaning them..spraying them with carb cleaner, brake cleaner, CRC , i took mine off and just sprayed the wire and it is better..but not perfect.