P0128 Jeep -

Question

2006 Jeep with 2.4 L 4 cylinder engine. OBD error code P0128 "Engine runs cold"
Engine CTS reads ambient ok. CTS reads 171-175 when engine is warm.
Intake air reads ambient ok and reasonable at operating temp (about 10 deg warmer then outside)
Changed thermostat and CTS sensor twice (last time used genuine parts). Still codes.
Flushed and changed engine coolant - still codes.
Measured 5 volts at sensor - Got it
Measure 0 ohms to battery ground - OK
Finally bought IR temp gauge and engine reads 195 deg at thermostat housing.
DOES ANYBODY HAVE ANY IDEAS! I'M STUMPED!!

Answer 1

Measure the sensor ground, this is not chassis ground, the color wire is DB/DG . With the multi meter one lead at battery negative or ground to the ECT sensor ground you should measure less than 0.2 volts