Ect sensor location

2006 2.3L Got a check engine light. AutoZone guy says it's due to coolant temperature (P0128). Temp gauge on dash never showed overheating. I'm thinking the sensor connections are dirty or the sensor itself is defective but I can't locate the ECT (Engine Coolant Temp) sensor. Anyone know where it is? Found out it has a CHT sensor (CYLINDER HEAD TEMP) and it's located between #2 & #3 spark plugs.