The EOBD system does not use any additional sensors or actuators to individually measure pollutants in the exhaust emissions.
The EOBD system is integrated into the software of the PCM and uses the existing sensors and actuators of the engine management system.
With the aid of these sensors, actuators and the special software, systems and components significant for emissions are continually checked during the journey and exhaust emissions calculated accordingly. Components significant for emissions are checked with the so-called monitoring system.
With the introduction of EOBD for European Ford diesel engines as of 1 January 2004 this will comprise the following monitoring systems (monitors):
โข monitoring of components significant to emissions (Comprehensive Component Monitors = CCM),
โข monitoring of the EGR system,
โข boost pressure monitoring,
โข fuel pressure monitoring
Monitoring system for components significant for exhaust emissions (CCM)
The monitoring system for components significant for emissions (CCM) continually checks to see if the sensors and actuators significant for emissions are operating within the specified tolerances when the engine is running.
If a sensor or actuator is outside the tolerance range, this is recognized by the monitoring system and a DTC is stored in the data memory.
Monitoring of the EGR system
The operation of the EGR system is monitored to identify faults that lead to increased exhaust emissions and may exceed the EOBD threshold values.
This monitoring system was developed so that it can, among other things, check the flow characteristics of the EGR system.
Boost pressure monitoring
Boost pressure control operates via the boost pressure control solenoid valve and the MAP (Manifold Absolute Pressure) sensor in a closed control loop.
The boost pressure is constantly monitored via the MAP sensor.
Fuel pressure monitoring
Fuel pressure monitoring operates via the fuel metering valve and the fuel pressure control valve. Feedback regarding the current fuel pressure is received via the fuel pressure sensor.