OBDII Components

Camshaft Position Sensor

The camshaft position sensor consists of a magnet, an iron core, and a pick-up coil. This sensor

Catalytic Converter

A Three-Way Catalytic (TWC) converter is used to reduce exhaust emissions.

Engine Coolant Temperature Sensor

The engine coolant temperature sensor is used to detect the engine coolant temperature.

Crankshaft Position Sensor

The Engine Control Module (ECM) detects engine RPM with the crankshaft position sensor.

Evaporative Emission System

The Evaporative Emission System (EVΑP) is used to reduce the hydrocarbons emitted into the atmosphere by the fuel system.

Exhaust Gas Recirculation

The Exhaust Gas Recirculation (EGR) system is designed to reduce oxides of nitrogen (NOx) emissions by lowering combustion temperatures.

Intake Air Temperature Sensor

The Intake Air Temperature (IAT) sensor is built into the Mass Air Flow (MAF) sensor or in some vehicles mounted to the air filter duct housing.

Knock Sensor

A knocking vibration from the cylinder block is sensed as vibrational pressure by the Knock Sensor.

Manifold Absolute Pressure Sensor

The Manifold Absolute Pressure (MAP) sensor generates a signal that is proportional to the amount of vacuum in the intake manifold.

Mass Air Flow Sensor

The Mass Air Flow (MAF) sensor is placed in the stream of the intake air. It converts the amount of air drawn into the engine ....

Oxygen Sensor - Air/Fuel Sensor

The oxygen sensor sometimes referred to as heated oxygen sensor, HO2S, or O2S. It is made of zirconia, platinum electrodes, and a heater.

Positive Crankcase Ventilation

The Positive Crankcase Ventilation (PCV) system provides effective evacuation of crankcase vapors.


The internal combustion engine cooling thermostat maintains the temperature of the engine near....

Throttle Position Sensor

The Throttle Position Sensor (TPS) responds to the accelerator pedal movement.

Vehicle Speed Sensors

Vehicle Speed Sensors come in several different designs depending on the manufacturer.

On-Board Diagnostic (OBDII) System FAQ