OBD-II provides access to data from the engine control
unit (ECU) and offers a valuable source of information when
troubleshooting problems inside a vehicle. The SAE J1979 standard
defines a method for requesting various diagnostic data and a list of
standard parameters that might be available from the ECU. The various
parameters that are available are addressed by “parameter identification
numbers” or PIDs which are defined in J1979. For a list of basic PIDs,
their definitions, and the formula to convert raw OBD-II output to
meaningful diagnostic units, see OBD-II PIDs. Manufacturers are not
required to implement all PIDs listed in J1979 and they are allowed to
include proprietary PIDs that are not listed. The PID request and data
retrieval system gives access to real time performance data as well as
flagged DTCs. For a list of generic OBD-II DTCs suggested by the SAE,
see Table of OBD-II Codes. Individual manufacturers often enhance the
OBD-II code set with additional proprietary DTCs.
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Now, you can select the trouble codes on the screen of your OBD2 scanner to see what is really wrong with your vehicle. Some OBD2 scanners
are more advanced and will actually tell you what the trouble codes are
and others will just give you the codes and you have a separate book
where you will look up these codes to find out what is wrong with your
vehicle. If you’ve just had your oil changed and they were unable to
reset or erase the trouble code that’s popping up the service light or
check engine light on your car you can actually easily erase this with
most OBD2 scanners.
All OBD2 code scanners come with a user
manual build a more in depth than this and you can actually track the
performance and output of your engine and vehicle. You can get your VIN
number and other pertinant data right from the code scanner. So now
you know how to erase erroneous codes so they don’t annoy you on your
dashboard. And you aren’t limited to just the car dealer for service.
At $50-$100 OBD2 scanners are definitely well worth having.