NeOmOrTaL

Has anyone of you guys ever had the OBDII P-code: P0101 when your CHECK ENGINE LiGhT came on? My light first came on after I ran out of gas in the middle of nowhere but I don't know if it relates to this problem. After getting it checked by AutoZone, they pulled up this TroubleShoot code: P0101 using their OBDII reader.

Here is what the code mean but I still have no clue on what needs to be fixed :

CODE P0101: " The PCM has determined that there is a discrepancy between the "actual" mass air flow input and the "calculated" mass air flow input derived from the input gathered from other sensors ie. throttle position sensor, barometric pressure sensor ect. "

Any help would be greatly appreciated... Thanks!

rallyeslide

Your engine has a sensor that is placed in the intake tubing that determines how much air is entering the engine.
The TPS [Throttle Position Sensor] tells the ecu the angle of the throttle plate, as well as how fast it is opening [if it is].
The barometric pressure sensor [MAP/Manifold Absolute Pressure] tells the ecu the actual air pressure inside the intake manifold.

Apparently the air flow sensor isn't telling the ecu the same thing the others are, ie the tps and map sensor are saying the engine is at full throttle, sucking in all kinds of air, and the air flow sensor is telling the ecu you're just idling along.
Or vice versa.

Could be a bad air flow sensor.
Could just be a dirty sensor, depending on what kind is in your car [I'm not too familiar with MB yet...]
Could be a bad connection.

NeOmOrTaL

Thanks rallyeslide. Thats alot easier to understand than the explaination they gave me. Your response is similar to what another member told me.... bad MAP sensor. If the sensor is dirty, is there a way to clean it or do I have to replace the sensor? Replacing it seems kind of expensive since I am a college student on a budget.

Anyone else had this problem and was the MAP sensor the problem? Any input would be greatly appreciated...

rallyeslide

It probably would be the air flow sensor and not the map sensor.
To clean it, pick up some electrical connector cleaner from an autoparts store, and CAREFULLY spray inside the sensor [after removing it from the car].
You might want to double check this with someone who knows MBs specifically, as I'm not sure exactly which type MB uses. Some of them can be rather delicate under certain conditions.

If no one else helps, post a pic up of the inside of the sensor and I let you know what to do exactly. As far as cleaning it and whatnot.

shorthair

There are a whole lot of existing posts about this error code and how to fix it, where to order it from at cheaper than dealer pricing, and the various methods of cleaning that people tried, which mostly don't fix the problem and you end up replacing the part anyway.

NeOmOrTaL

From my understanding, I will try to remove both the air flow sensor and the MAF sensor to clean it. I have search other threads and it seems to be the MAF sensor... so I am probably going to try that first.

Thanks to everyone who has help me with this issue. Its nice to know friendly tech support is only a few clicks away.

NeOmOrTaL

Thanks shorthair for your help. I have searched the board and it seems like cleaning it seems to be first thing I should do instead of going to the dealership only for them to tell me to replace it when it just needs cleaning.

Btw guys, I am at 90K miles but its an 02 C230. At this high of a mileage, is it normal to replace it or is it still worthy of cleaning it only to have it go bad again?

Air Marshall Eldritch

I know a guy that sells new ones for around $161 if you need it. Beats the dealer price by a fair bit.

rallyeslide

The MAF sensor IS the air flow sensor. MAF = Mass Air Flow