It will read cold most of the time. It takes sped load and torque to get it up to show much temperature. Climbing a mountain it will show especially if towing a vehicle. In hot weather it will, of course show earlier. Took ours to Freightliner then Allison shortly after buying it because we thought the trans temp gauge was not working properly. All was fine. That was 2005 model. newer ones I cannot say. Take yours to the factory or to the chassis mfg service service center and have it checked.