Hummer 12589867 Sensor,Knock

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The removal process starts by disconnecting the cable from the battery's negative terminal. On 5.7L (LS1/LS6) engines, take off the intake manifold. From valley cover, remove grommets and lift them up to separate them electrically from knock sensors. Take out the screw for the knock sensor(s). For 6.0L (LS2), 6.2L (LS3/LS9) and 7.0L (LS7) engines, jack up the car then securely place it on jack stands. Eliminate engine compartment under-covering. The Bank 1 knock sensor is located at left side of engine block just in front of oil filter housing location while Bank 2 knock sensor is situated at right side of engine block just ahead of starter position. Eliminate exhaust manifold. Remove upstream cataytic converter; Remove bolt in center of Knock Sensor, then remove Knock Sensor; Unplug electrical connector from Knock Sensor; Reverse Installation: For installation, it is opposite procedure as described above.; Tighten Knock Sensor or Knock Sensor Bolt to specified torque setting for each bank.

Knock sensors in the engine sense unusual vibration and diminish spark knock. They give AC output voltage that increases with the severity of the knock. The PCM receives the signal and retards timing to compensate for detonation. The 4.2L six-cylinder engine has two knock sensors, with sensor 1 located towards the front and sensor 2 towards the rear. Knock sensor system can be affected by premium or high octane fuel, thus creating false codes. To replace the knock sensors, disconnect the negative battery terminal, raise vehicle and secure on jackstands. Disconnect knock sensor electrical connector and remove sensor bolt. For V8 models from 2002 to 2004, remove intake manifold and detach grommets and electrical connector off valley cover. Take out knock sensors from engine block. For V8 models from 2005 and later, disconnect negative battery cable, raise vehicle and support on jackstands. Disconnect electrical connector and take out right side knock sensor from cylinder block. Repeat for left side.

To remove the knock sensor on a vehicle, loosen the front wheel lug nuts and raise the front of the vehicle on jack stands. Remove the wheel and the knock sensor heat shield retaining bolt. Disconnect the electrical connector and remove the retaining bolt to take out the knock sensor. The installation is the reverse of the removal steps.

On 4.8L, 5.3L and 6.0L V8 engines, the two knock sensors are located on top of the engine, underneath the intake manifold. The intake manifold needs to be removed to access the knock sensor(s).