Cooling Problems and Gas Mileage

I have a 1996 Blazer 4.3L W-engine. It has about 95,000 miles on it.

The enginer temp gauge is showing 125-130 degrees while my friends Matco scanner shows that is is actually running 190-195 degrees. Is there a way to check if it is the gauge or the sensor?

It is also showing codes SO131 and SO151. It reads as low oxygen sensor voltage for both. Does anyone know which sensors these would be? Is there a way to test the sensors? We also noticed that the scan tool was always showing the air/fuel mix as lean on both banks. I assume that the computer is dumping fuel into the engine to compensate. I am getting only about 12mpg city. Could this be causing this?

Thanks

Gregg
1996 Blazer 4.3L W-engine

could be an exhaust leak causing it, a bad PCM ground or grounded O2 sensor signal wires

i wouldn't worry about the gauge too much i think there are 2 coolent sensors on the block one for the gauge and one for the comp


there is a way of testing the o2 but it involve a multi meter . i think that year has 4 o2 in it and all of the are 4 wire. what u gotta do is find the ground for the o2 i cannot remember what wire it is and measurethe resistace and compare all off them. 1 o2 being off can fudge alot up