As mentioned it may need calibration
You can calibrate it in a pot of boiling water. Loosen the nut under the dial and slightly rotate dial to match boiling temp at your altitude. An easy rolling boil is good.
Calibration can be upset by using the dial to screw the dip stick in. Avoid using the dial. Use the stem instead and finger tight is good.
Sea Level 212 degrees F
984 ft. 210 degrees F
2,000 ft. 208 degrees F
3,000 ft. 206 degrees F
5,000 ft. 203 degrees F
7,500 ft. 198 degrees F
10,000 ft. 194 degrees F
20,000 ft. 178 degrees F
26,000 ft. 168 degrees F - The death zone
