Join Date: Oct 2011
Location: Magnetic Hill, New-Brunswick
Worrying for nothing.
This is all normal, when temperature reaches a predetermined value fan or fans come on and bring temps down then shut off until temps reach these value again. The two fan speeds are determined by coolant temperature. The PCM commands Low Speed Fans ON under the following conditions:
• Engine coolant temperature (ECT) exceeds approximately 106°C (223°F).
• A/C refrigerant pressure exceeds 1 310 kPa (190 psi).
• After the vehicle is shut off, the ECT at key-off is greater than 140°C (284°F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.
The PCM commands High Speed Fans ON under the following conditions:
• ECT reaches 110°C (230°F).
• A/C refrigerant pressure exceeds 1 655 kPa (240 psi).
• When certain DTCs set
You should worry about the thermostat when vehicle engine operating temperatures are not reached. Because the thermostat is set to open at 192°F (89°C), as a thermostat ages it opens more and more at lower and lower temps because the spring gets weak. At one point it will set a code and your check engine light will come on because your engine did not reach a preset value in a preset amount of time.
It will be one of these codes depending on what type of thermostat failure...Most probably a P0116 or P0126.
P0115 Engine Coolant Temperature Circuit Malfunction
P0116 Engine Coolant Temperature Circuit Range/Performance Problem
P0117 Engine Coolant Temperature Circuit Low Input
P0118 Engine Coolant Temperature Circuit High Input
P0119 Engine Coolant Temperature Circuit Intermittent - see our "articles" link for additional help with these generic check engine light codes
P0125 Insufficient Coolant Temperature for Closed Loop Fuel Control
P0126 Insufficient Coolant Temperature for Stable Operation
Never drive faster than your guardian angel can fly
Last edited by Coby7; 04-20-2013 at 05:56 AM.