1991 Audi 100 Mass Airflow Sensor Replacement Cost

The engine's computer has to receive input from many sensors, and ensure they are in agreement. An extremely important sensor that is used in reference to nearly all engine operations is the mass airflow (MAF) sensor. The MAF sensor records the volume of air that enters the engine's intake tube, and reports that information to the computer. This allows the computer to calculate, or confirm, the amount of air moving into the engine, amount of exhaust gas to expect, the amount of fuel to send into the engine, and many other important factors. Lastly, this sensor works very closely with the manifold absolute pressure (MAP) sensor to allow extremely accurate response to changing conditions.

If the MAF sensor sends an erroneous signal, a few things happen. The engine's computer will trigger the check engine light, and the on-board diagnostic (OBD) trouble codes will reflect the airflow discrepancy noted by the MAF sensor. Depending on the reported volume of air, the engine may try to compensate for these conditions, causing the engine to burn excessive amounts of fuel and emit black smoke from the exhaust. In this case, the OBD trouble codes would also reference faults recognized by the exhaust oxygen sensors. The engine may also have issues with idling roughly, failing to start, stalling, hesitation, power loss, misfires, and fuel consumption. »MORE: Signs of a failing mass airflow sensor