Understanding OBD2 Diagnostics
Trying to understand OBD2 diagnostics, the information available through OBD has varied widely since the introduction in the early 1980’s of OBD computers, which made OBD1 possible. When OBD was first applied, it would show a check engine light or CEL, if a problem were detected. The problem is, it would not show any solution as to the exact nature of the problem which makes OBD1 difficult to use. On the other hand, the OBD2 standard specifies the electrical signaling protocols available, and the messaging format thus leading you to the suspected circuit. It also provides a candidate list of vehicle parameters to monitor along with how to interpret those parameters. All of these is given on the instruction manual that comes with the code reader.
With the introduction of OBD2, it is quick and easy to understand the cause of a vehicle’s Check Engine light (DTC) problem because it will display generic and manufacturer-specific diagnostic trouble codes along with their detailed descriptions. Some OBD2 software also provides access to Freeze Frame data which records the status of vehicle sensors at the exact point in time that the Check Engine light was triggered. The Check Engine Light (CEL) will illuminate anytime a vehicle’s emissions exceed 1.5 times the federal test procedure standards for that model year of vehicle. Some codes require the faulty condition to occur twice before the MIL comes on. This is performed since any defect in any of these systems could cause vehicle emissions to surpass the allowed level. The electronic components being monitored can include such sensors dealing with engine rpm, throttle linkage position, engine coolant temperature setting, crankshaft angle, engine knocking, fuel chemical breakdown and others.
Like the OBD1 that was used before, OBDII is a new government regulation mandated to lower car emissions. However, what makes OBDII to stand out is its user friendly application that is adaptable for all newer vehicles like car and trucks that cover most imported and domestic vehicles.
