Why does the panel engine coolant temp. gage goes out on my 2008 HHR Chevrolet?

There are great threads on this at http://chevyhhr.net - Patrick is right but in simpler terms it is either the sensor or the thermostat being stuck open. P0128 is the code that shows when the sensor is shot. Known issue. It's doing it on mine too. :)

I guess first it needs to be properly diagnoised, using a proffesional grade scan tool I would look and see if the computer is reading the input from the coolant temperature sensor, the information can be read right off the scan tool if the scan tool says zero the input side of the computer is bad.. Next the circuit to the gauge needs to be checked. For test procedures there is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online Removal of the instrument cluster takes about .6 hour labor add time for diagnostics.

I just changed the thermostat on a 2008 hhr and fixed this problem but there is an info button on the steering wheel just push it until it displays coolant temp it should be between 180 and 200 degrees when car is fully warm at operating temperature mine was at 135 before i fixed it now it reads 192 and light stays off after i erased codes with scanner