OBD-II and your car’s health

Due to the investment in the equipment required, most repair shops charge a fee, some-times substantial, to attach the scanning equipment and diagnose problems using the OBD-II system signals. Home mechanics and small shop technicians have been restricted from working with these signals by the cost and technical complexity of the equipment. With the introduction of more economical and user friendly scanning devices, it is now practical for almost anyone to access OBD-II signals and use them for their own testing and repairs.

Scanners vary greatly in their complexity. The best connect easily and use software to quickly and automatically call up the OBD-II information. A system connecting to a laptop or desktop computer provides expanded memory for data and a graphing utility.

Proprietary Sensor Readings

Though not part of the EPA’s OBD II standard, the diagnostic read-outs used by dealership technicians are also read through the OBD II connector. These service codes show you such things as knock sensor operation, FI pulse width, ignition voltage, individual cylinder misfires, transmission shift points and ABS brake condition.  There can be over 300 readings available, depending on the vehicle manufacturer and model. Vehicles vary in the readings they will support. Scanners vary widely in the number of these signals that they can read.  Some show just the basic OBD or OBD II signals, others show the full range of service codes.

OBD-II and performance tuning

While the vast number of drivers want nothing more than dependable, economical transportation, many of us are looking to OBD-II for extra performance. Earlier on-board computer systems had chips that could be replaced to adjust engine parameters for extra speed and power. While the OBD-II systems are sealed and do not allow chip replacement, they do provide a real time data acquisition system that is useful to tuners.

Power loaders can actually reprogram the performance parameters of the OBD-II system to accommodate performance options. At the current time the number of models they can service is limited, but the range is being extended. Be sure the person doing your reprogramming keeps the car in compliance with EPA emission standards. As aftermarket manufacturers develop additional solutions, we will add their information to our links.