Cel

Grandsons 2001 Elantra and about six months ago she lit the CEL up and she coded out temp sensor bad. I replaced the temp sensor and the thermostat since I was in the area and all was well. Now, with winter here she has once again lit the CEL and once again coded the temp sensor is bad. Warm weather OK, cold weather not OK, is this an anomaly, anyone else had this issue?