Chris... work with us a little here.... post the year, engine size, etc.
here on the NG rather than sending it PM to me.... Also... has the gauge
failed in the "cold" area or is it reading at the top of the scale?
FWIW, I rarely bring home the PC/ED any more... however.... you do have two
symptoms that may share causes....
For the check engine light, I would have the codes read... I can't recall if
your temp gauge and PCM share coolant temp information, but the possibility
is very real. At any rate, there is no CEL diagnosis that can mean anything
without knowing what the PCM is trying to tell, us. If time allows (and,
sadly, I am about 4 days behind at work... in spite of working until near
midnight tonight ), I'll endeavour to check the manual tomorrow - no
At the same time, CEL diagnosis *may* affect the temp gauge diagnosis -
What you can do in the meantime.... look at the temperature sender to see if
it is still connected (not sure if you have one or two). If your temp sender
has two wires, unplugging it should make the PCM "see" -40 degrees...
shorting the two together (beinf careful not to spread the connections)
should deliver a very high temp reading... At the same time, check the
connector and the sender for corrosion and damaged or pushed out pins....
Again, I cannot stress the importance of checking for codes and also the
importance of being sure all warning devices are functioning properly...
Lastly, please do not PM me asking for assistance... Any diagnostic advice
or efforts should be done on the NG so that we can all learn from the