OBD-II FAQ about Jaguars

Can i Reprogrammed the performance options set on my car and introduce new features.

No. OBD is a diagnostics system it was never developed or intended to be used as a computer controlled programming module and for very good reasons this type of work is best left to the trained, qualified professionals who understand what is involved. If this facility was easily accessible it would be very easy to find yourself with at best a dead car and at worst an extremely dangerous car that could kill the driver and other road users if for instance the brakes suddenly switched mode and failed following changes made by an inexperienced user.

Can I read codes on my Jaguar?

Yes you can: you can read fault codes from sensors fitted to the cars engine and other components when an error has been detected, you can also monitor certain sensors in real time where that sensor passes information to the cars Diagnostic interface. Not all sensors are monitorable although fault codes can be reset on most; some systems operate independently from the OBD system and you can only monitor systems where a compliant sensor is fitted. This is a limitation set by Jaguar not a limitation of the scanner.

Why is that, surely OBD-II is a standard?

From around 1996 cars destined for the USA market were required to carry OBD II diagnostics as part of the clean air act. For some manufactures this presented them with a problem, Should they build cars with different specifications for different markets? For most this would prove to be very costly as it would mean retooling for these various markets. In the case of Jaguar they opted to standardise across the range regardless of intended market.

!996 saw the first of these cars in the form of the XJ6 (X300) and a little later the XK. These early cars had many sensors around the car which controlled the engine management and some suspension components such as traction control and ABS and a few cars that had the new electronic gearboxes fitted to certain spec cars.

The guidelines were somewhat open to interpretation during these years and not all items were included in the OBD-II diagnostic protocol in that some sensors would not communicate directly with the OBD system interface passing only a flag when an error occurs meaning that things like ABS sensors, gearbox oil temperature etc can not be monitored and the only indication that there is a problem is when the relative warning light comes on.

Early OBD-II is there for limited to the car manufacturers settings, A scanner, such as the ones we sell, although capable of reading the various sections are only able to report those monitored via the OBD-II system as defined by the car manufacture.

This was obviously not the best solution ongoing global pressure on emissions saw  the European community set about introducing a new standard in OBD in 2001 – this was to be known as EOBD-II a complete new set of standards and requirements were put into place. This required all major sensors fitted to the car to send communication data to the OBD system processor, this not only enabled the external interface to reset individual sensor but with the right external hardware top level monitoring of sensor data in real time.

A popular misconception is that all systems are included in OBD and EOBD. This is NOT the case as manufactures only comply to provide the minimum set of monitoring to protect there revenue trough authorised dealers and from there own diagnostic equipment costing many more thousands than those available to the open market under the OBD-II legislation.