What are fault codes?
Before OBD-II, each manufacturer had a specific trouble code list and code definitions. Under the OBD-II requirements, all manufacturers must comply with a standardized convention for Diagnostic Trouble Codes (DTCs). These fault codes are stored in the vehicle’s computer to indicate which system or component might be causing the problem. These fault codes can help technicians to make effective and efficient repairs.
Fault codes are recognised problems or faulty sensors to the EMU (Engine Management Unit) which is a ECU (Electronic Control Unit). The ECU relies on the sensors on your car to make it run at it’s optimum performance at all times. When a sensors goes wrong or there is a fault with the engine, the ECU sees this problem and logs the fault code within it’s memory (NOTE: not ALL problems are logged, depends on what system your car has). Often the ECU warning light on the dash board may light up, indicating to you that there is a problem. NOTE: The ECU warning lamp usually needs to be on for more than 30 seconds before the ECU logs a fault code. Otherwise it could consider it an intermittent fault and ignore it. Do all ECU’s handle fault codes? If your engine is fuel injected then it needs a ECU to control the injection timing. All Vauxhall models that have injection need a ECU to do this and hence they will have the facility to log fault codes. If your engine is run on a carburetor, then i
