Fabian's Mechanical







bullet Scan tool (tool used in Dealerships)
bullet Fault Finding live data readouts
bullet Diesels including Common Rail
bullet Petrol EFI (Fuel Injection)
bullet ABS & Traction Control Systems
bullet Function tests
bullet Computer Diagnostics
bullet Check live data & fault codes
bullet Body Control Modules
bullet Code Clearing Service
bullet Transmission function tests
bullet Discover non-reporting faults
bullet Service Light Resetting
bullet Can Bus fault finding
bullet Injector testing and cleaning


Most modern vehicles have a computer or ECU (Electronic Control Unit), PCM (Powertrian Control Module) that controls engine and or transmission operation, as well as a host of other important functions like brakes, lights, air bags, security, traction control, suspension, climate control just to name a few. The main purpose of this is to keep your vehicle running at top efficiency with the lowest possible emissions, safety & driver/operator comfort. With today's strict emission regulations it's not very easy to achieve. The engine needs to be constantly and precisely adjusted according to various conditions such as speed, load, engine temperature, fuel quality, ambient air temperature, load conditions, etc. A number of sensors provide the ECU with all of the necessary information to run the engine at best performance under any situation. According to these inputs, the ECU makes adjustments like adding or subtracting fuel, advancing or retarding the ignition timing, increasing or decreasing idle speed, etc.

There is also sensors installed in the exhaust before the catalytic converter or dpf that monitors the quality of combustion in the cylinders. Based on the feedback from these sensors the ECU makes fine adjustment to the engine to further reduce emissions, maintain peak performance & fuel economy .

The ECU which may also control a host of other functions has a self-diagnostic capability and constantly tests the operation of sensors and other components. When any of the sensor signals is missing or out of normal range, the ECU sets a fault and illuminates the "Check Engine" or "Service Engine Soon" light also called MIL (Malfunction Indication Light) storing the corresponding Diagnostic Trouble Code (DTC) in the ECU memory

The same will happen if a mechanical component of the controlled system fails. For example, if the EGR valve fails, this will also cause the "check engine" light to come on. The vehicle may go into "limp mode", or shut down completely.

The stored trouble code can be retrieved with a diagnostic tool (Scan tool). The code itself does not tell exactly which part to replace, it only gives a direction where to look for. It is then up to the Technician to use his knowledge and experience to correctly identify the fault. Some faults are caused by faulty wiring, corrosion, loose connections, or a broken or intermittent break in a wire, which can be time consuming to locate.


Send mail to mech@fabian.net.au with questions or comments about this web site. RTA # AU02851
Last modified: 07-Oct-2009
copyright fmm 2017