Where Is the Knock Sensor on a 4.3 L Vortec Engine?by Justin Chacos
Chevrolet’s 4.3-liter Vortec V-6 engines incorporated one or two knock sensors. These sensors detected incorrect fuel-air mixture combustion in the cylinder. The knock sensor relayed the information to the engine control module, which adjusted engine timing to compensate for the knock.
1994 and 1995
The 1994 through 1995 Vortec V-6 engines had two knock sensors -- one located on the driver’s side of the engine block between the rear-most and middle cylinders, and the other is on the passenger side, either on the rear of cylinder head, or on the block between the rear-most and middle cylinders.
1996 through 1999
The single knock on the 1996 and later Vortec engines was located at the rear of the engine, below the driver’s side of the distributor. It was directly behind two rigid fuel lines leading to the intake manifold.
The knock sensors in 4.3-liter V-6-powered light pickups, such as the C1500 and Silverado, were in slightly different locations than the SUV and passenger vans. The pre-1996 models had two sensors, one on each side of the block. The later year models had a single knock sensor mounted in the engine block in front of the starter.