[masraum]

OBDII was mandatory starting in 1997.

I have a ScanGauge 2, www.scangauge.com. It's a great little tool. You can read codes, read the data that the ECU captures for various parameters when it captures a code, reset codes, but then it does a lot more. It's about $160, but it's worth it IMO compared to spending almost as much for a tool that does less.

(they are getting ready to release a FW upgrade that adds several enhancements to the functionality listed below.)

Trip computer
» Maximum Speed
» Average Speed
» Maximum Coolant Temperature
» Maximum RPM
» Driving Time
» Driving Distance
» Fuel Used
» Trip Fuel Economy
» Distance to Empty
» Time to Empty
» Fuel to Empty

Digital Gauges
» Fuel Economy
» Fuel Rate
» Battery Voltage
» Coolant Temperature
» Intake Air Temperature
» Engine Speed (RPM)
» Vehicle speed (MPH)
» Manifold Pressure (not available on some vehicles)
» Engine Load
» Throttle Position
» Ignition Timing
» Open/Closed Loop

Scan Tool
» Reads Trouble Codes
» Reads conditions that set the Trouble Code
» Clears Trouble Codes
» Turns off "Check Engine" light
» Tells you when vehicle is "Ready" to pass OBDII testing
» Make and store up to 10 rewritable special codes to send to the vehicle computer