Hyundai Repair: help, digital voltmeter, oxygen sensors

Question
hi, do you know where can i buy good & cheap OXYGNE SENSOR TESTER (diagnostic tool) for oxygen sensors. ANY MODLE # OR WEB WHERE I CAN BUY
THANKS

Answer
I don't know of any tool specifically designed to test oxygen sensors.  There are several inexpensive code readers out there, but these will give you trouble codes, not find the cause of the code.  

Probably the cheapest tool to use to diagnose an oxygen sensor is a digital voltmeter.  Simply monitor the voltage output of the sensor once the car reaches operating temperature, and you should see it switch from high to low voltage at least once every three seconds.  You can also use a scan tool to do this, but I don't know of any inexpensive scan tools.  

You should be able to purchase a code reader at your local parts store.  For the voltmeter, you could probably get one that's good enough for what you want at Radio Shack or similar place.