check gauges light & temp gauge
 

My 04 Jeep Grand Cherokee's check engine light came on 2 weeks ago the same
day the motor for my driver side window died. I took the car in and had the
window motor replaced & a temp coolant switch replaced. Since then the check
engine light came back on & after having the codes read - the verdict is
"engine coolant temp circuit low" - the check gauges light then came on the
next day and the temp gauge reads anywhere from 100-240 and hits the red line
at least 1 time per car trip over the last few days. This is still happening
after replacing the thermostat 2 days ago. Im at a loss for what to "fix"
next to get this resolved. The car seems to be running fine- but it really
freaks me out when the temp gauge goes crazy and my check engine/gauges light
comes on.
The Jeep has 67000 miles on it -
any advice?