2008 GMC Envoy Denali (short wheelbase), replaced all four TPM sensors in February 2016 with AC Delco sensors. Immediately after replacing the sensors the dash light came back on and the LF stopped reading intermittently, worse when it was colder (below 40F). The truck stays inside in a heated garage. In March, I had the LF replaced again at the dealer and the light came on again. First the tire pressure reading is shown, then after driving a bit more just dashed lines show up, then after a little farther it starts reading again. Then after doing a key cycle the light goes back off and stays off. The other wheels don't have this issue and the dealer would not diagnose it unless the TPMS light is on and the sensor reading is dashed lines. We have taken it in several times, first all they did was re-teach the sensors and then lastly replaced the BCM in April after they were able to get the DTC for the left front. After the BCM replacement there have been no TPMS lights all summer until recently when the temps began cooling off over night in the 50's. After about 15/20 minutes of freeway driving (65-75mph) the TPMS light will come on, left front will be dashed lines on the DIC. Turn off the freeway onto a 2-lane county road (55mph) and the left front will begin reading again but the TPMS light stays on. In the afternoon, after work, ambient air temps in the 70's/80's no TPMS light at all. Anyone else have issues with just the LF wheel sensor? Is the receiver module starting to have issues in the tailgate? All lift gate functions work, wiper, defrost, keyless entry, etc. I have rotated the tires a couple times since the sensors were installed and they register correctly when you go through the re-teach procedure in the owner's manual. **should've have stated when the dash light comes on it flashes and the DIC says "Service Tire Monitor" then after about a minute the dash light stays on solid. According to GM document #07-03-16-004B this flashing indicates a system malfunction but does not elaborate any further and what is malfunctioning other than the sensor may not have transmitted info for 18 minutes of driving.