My 82 240 has 3 temp sensors/switches. The one in the center of the engine under the intake manifold is for the temp gage, the one at the rear of the head under the intake manifold is for the cold start injector, and the one at the front of the head under the intake manifold is for the lambda system. The center one is a PITA to change without removing the manifold. The front and rear are somewhat accessible and can be changed with the intake intact. If I could find a good used sensor, I would install it.