97 tahoe p0125

I have a 97 tahoe that starts fine when cold but is had to start once warmed up. It threw a code p0125 saying it has not reached full temp stays open loop. My temp guage says 195 degrees but the scanner says 50 degrees. It has 145K and the intake gaskets were replaced 20k ago. Any help would be appreciated. Tom

I have a 97 tahoe that starts fine when cold but is had to start once warmed up. It threw a code p0125 saying it has not reached full temp stays open loop. My temp guage says 195 degrees but the scanner says 50 degrees. It has 145K and the intake gaskets were replaced 20k ago. Any help would be appreciated. Tom

My bet is on a stuck thermostat.

Faulty temp sending unit?

You don't say what engine. Typically there are two sensors. One in the drivers side head for the gauge and one in the intake manifold by the t-stat housing for the VCM. This 2nd one is the problem. Check wiring and/or replace this sensor.