Mass Air Flow Sensor

The mass air flow sensor works in conjunction with the oxygen sensor and the engine control system. While the oxygen sensor determines the oxygen levels in the exhaust system, the mass air flow sensor is used to monitor the amount of air passing through the engine while running. A vehicles mass air flow sensor delivers a signal to the ECM (engine control module). It is usually difficult to detect when a mass air flow sensor fails. The "check engine light" or engine symbol will probably not be illuminated. Your car, truck or SUV may have a poor idle quality, stall, low power or all three. Your PCM may have no trouble codes because the ECM cannot detect a problem

What has occurred is the sensing element or "hot wire" that is used to give electronic feedback to the ECM for processing has become contaminated by air partials. The mass air flow sensor is reporting to the ECM that less air is running through the engine than actually is. The ECM will then lean the fuel mixture down to the point of run ability problems. There is not enough variance in the system to trigger a MIL (malfunction indicator light) - "Check Engine" light so this particular repair problem can be difficult to detect through normal trouble shooting methods.

A mass air flow sensor is most common in newer vehicles, this sensor is used to help maximize efficiency and reduce emissions. One of the benefits of the mass air flow sensor is that it can vary responding to changes in air intake flow. There are no moving parts in a mass air flow sensor. Most vehicles mass air flow sensor locations are in the air intake for the engine, this allows easy replacement. It is recommended that the sensor be replaced approximately every 60,000 miles..