Mass Airflow (MAF) Sensor (Freelander)

MAF sensor provides a signal the ECM uses for engine load calculations. The MAF sensor is a hot film type, and is located in the intake system between the air filter housing and throttle body. A closed-loop control circuit in the MAF sensor maintains a thick film resistor at a constant 392°F (200°C) above ambient temperature. The current required to maintain the thick film resistor temperature, against the cooling effect of air flowing through the sensor, provides a precise, non-linear, measurement of the air mass entering engine. The MAF sensor receives a battery voltage power supply and generates an output signal to the ECM, between zero and 5 volts, which is proportional to the air mass drawn into the engine. If there is a MAF sensor signal failure, the following symptoms may occur:

• While driving, engine speed may dip before recovering.
• Difficult engine starting.
• Engine stall after starting.
• Delayed throttle response.
• Reduction of engine performance.