Mass airflow sensor
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Mass airflow sensors detect the mass of air entering the engine directly, using a hot wire, or a heated ceramic plate resistor.
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Manifold absolute pressure sensor
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Manifold absolute pressure sensors measure changes in intake manifold pressure caused by changes in engine speed and load, and convert them into electrical signals.
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Air vortex sensor
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The air vortex sensor uses whirlpools of air, produced by a vortex-generating rod, to measure the volume of air entering the engine. This is converted to an electrical signal that is transmitted to the ECU.
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Fuel system sensor
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Sensors detect engine conditions and relay information as electrical signals to the ECU. It determines how much fuel the engine needs at that instant, then grounds the injection valve circuit, to open the solenoid-operated injectors.
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Temperature sensor
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Temperature sensors relay information to the ECU on engine coolant and intake manifold temperature.
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Throttle position sensor
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Throttle position sensors relay information to the ECU on throttle position, to allow adjustments to fuel settings, according to operating conditions.
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Exhaust gas oxygen sensor
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Exhaust gas oxygen sensors monitor the oxygen content of the exhaust gas, and relay this information, by means of a voltage signal, to the control unit.
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Crank angle sensor
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Crankshaft position and speed can be detected by inductive-type sensors which act as small alternators. The frequency of the pulse they transmit allows the ECU to detect engine speed.
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Hall effect voltage sensor
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A Hall effect sensor provides voltage pulses that are generated by alternately shielding the sensor from a magnetic field, then exposing it. An ECU uses this signal to detect engine speed and control ignition timing.
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| OBD and EOBD |
Prior to the advent of digital powertrain control modules which enabled the OBD feature, repairing a vehicle relied solely upon the technician's skill and service literature from the auto manufacturer. |
