V50 L5-2.4L VIN 39 B5244S7 (2005)
The mass air flow (MAF) sensor is positioned between the air cleaner (ACL) housing and the intake manifold.
Mass air flow sensor
The mass air flow (MAF) sensor gauges the air mass sucked into the engine. It continuously transmits signals to the engine control module (ECM) about
the mass of the intake air. This data is used by the engine control module (ECM) to calculate:
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the injection period
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the fuel pressure
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the ignition timing
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the engine load.
The transmission control module (TCM) also uses this data for its gear shift calculations. This data is transmitted to the transmission control module
(TCM) from the engine control module (ECM) via the high speed side of the Controller area network (CAN).
The mass air flow (MAF) sensor is a hot wire type. Unlike other hot wire types, the mass air flow sensor in the Denso system uses a hot wire which has a
ceramic casing. This eliminates the need for a clean burn function.
The mass air flow (MAF) sensor is supplied with battery voltage by the system relay and is grounded in the engine control module (ECM). The signal
from the sensor is analogue and varies between approximately 0.5-4.5 V depending on the air mass. Low air flow (low mass) results in low voltage, high
air flow (high mass) gives high voltage.
On turbocharged engines the mass air flow (MAF) sensor has a slightly different design. It is not a combined sensor and only contains sensors for the
mass air flow.
The engine control module (ECM) can diagnose the mass air flow (MAF) sensor. The signal can be read using VIDA.
Temperature sensor
The temperature sensor checks the temperature of the intake air in the intake manifold. This data is used by the engine control module (ECM) to
calculate injection period. The control module also controls certain diagnostic functions using the signal from the temperature sensor.
The sensor, which is an NTC resistor, is grounded in the control module and supplied with power (signal) from the control module.
The resistance in the sensor changes according to the temperature of the intake air. This provides the control module with a signal of between 0.5-5 V.
The lower the temperature the higher the voltage (high resistance). A high temperature results in low voltage (low resistance).
The engine control module (ECM) can diagnose the temperature sensor. The sensor signal can be read using VIDA.
Manifold absolute pressure (MAP) sensor
The manifold absolute pressure (MAP) sensor is on top of the radiator and is connected to the intake manifold by a hose.
The manifold absolute pressure (MAP) sensor detects quick pressure changes in the intake manifold after the throttle. The signal from the sensor is used
by the engine control module (ECM) to supplement the mass air flow (MAF) sensor when calculating injection period.
The semi-conductor sensor is grounded in the control module and is supplied with power from the control module.
The resistance in the intake manifold moves the silicone membrane in the sensor, giving a signal of 0.5 - 4.5 V. Low pressure results in low voltage, high
pressure in high voltage.
The engine control module (ECM) can diagnose the manifold absolute pressure (MAP) sensor. The sensor signal can be read using VIDA.
Leak diagnostic unit (certain markets only)
