The old sensor got broken during a accident with a deer. I've replaced the sensor and it's reading -40 deg. Is there a reset on this unit? The sensor worked about a year after the wreck until the plastic end finally broke off. What's the secret to getting it to read at all?? Is it in the computer chip or do I have a wire that is shorted out?? Any help would be appreciated.
The wire going to the sensor is not connected (most likely) or is grounded out somewhere. It's also possible that the switch is bad, but you said you have replaced it.
-40 is the lower limit, it will read -40 when it's unplugged or grounded depending on how it's set up, most are set up for the former.