There are 2 knock sensor on the 5.3L engine. And they are under the intake manifold.
To get to them you will have to remove the whole top of the engine- INTAKE MANIFOLD. Why do you think they need replaced???? check engine light came on for 2 sensor
The oil pressure sensor, on your 2003 Chevrolet engine, is located on the front of the engine, just above the oil pan. The pressure sensor will have two wires going to it.
The 2003 Chevrolet Suburban has a V8 engine.
The 2003 Chevrolet Corvette has a V8 engine.
The 2003 Chevrolet Express has a V6 engine.
The 2003 Chevrolet Malibu has a V6 engine.
The 2003 Chevrolet Tahoe has a V8 engine.
The 2003 Chevrolet Impala has a V6 engine.
Driver side engine block behind the alternator.You need to remove the alternator to get to the sensor.
Just above the top radiator hose the leads into the engine.
It is bolted in the side of the engine block behind the starter. You will have to remove the starter.
The 2003 Chevrolet Express-Cargo has a V6 engine.
The 2003 Chevrolet Silverado-1500 has a V6 engine.