Hey, all...my check engine light came on over the weekend, so, I took it to Autozone, and, they pulled a P0128 code. Now, with that being said, I also had my car scanned at my dealership I work at, and, they pulled the same code. It was low on coolant (I had topped off the coolant already), and, the tech cleared the code, and, the light didn't come back on. Now, could someone tell me where the engine coolant temp sensor would be on my '03 Malibu with the 3.1 engine? Is it next to the thermostat? Would this be an easy fix for an amateur mechanic like me?

the code is that the temp doesnt come up within a certain time period, its likely the sensor is good but needs thermostat changed. good time to change your coolant as well if you havent recently. if you have a scanner with live data you can confirm this by reading the coolant temp at operating temperature and shooting the thermo housing with a ir gun and compare.