2003 Silverado 200K miles P0332 Knock Sensor 2 circuit Low input bank 2. Starts and runs smoothly with no loss of power or decrease in gas mileage. Should knock sensor(s) be replaced and what is the expected cost at a dealer.

 

Knock sensors are under the intake manifold. There are two, and they each sit in a dedicated well between the heads. The little well is sealed by a big gasket that the sensor wire passes through the middle of. The gaskets rip, letting water in. You'll find one or both sensors sitting in rusty water. Cover the intake ports on the cylinder heads and blow all that crap out before you unthread the sensors. This will keep the threads from getting contaminated. Buy a new harness, as it's just a short 2-wire jumper. They're super cheap and this is common enough that you can find kits with both sensors and the harness. The harness by itself is about $15.

The intake manifold gasket may need to be purchased separately. Just look up a video on youtube of removing the intake. Make sure you get everything nice and clean for he new gasket. Also remember you need a fuel line disconnect tool. The intake isn't hard. The most difficult part is manipulating the intake manifold around as you're trying to take it off, because the semi rigid hose to the purge solenoid passes between the intake and the fuel rail that's secured to the intake, and the semi rigid hose has a 90 degree bend at the end.

Don't over tighten the intake bolts. They're very small. Check the torque spec.