240sx knock sensor replacement

Knock Sensor Replacement

By: Anibal Betanzos

First, let me say that I scratched my head for several days before trying to replace the knock sensor on my car.Because as we all know it is hidden way up underneath the intake manifold next to the engine block. I almost considered dismantling the intake manifold in order to have better access to that area, but then I thought, “why should I risk warping or damaging such a sensitive area that already works just fine…in addition why should I have to unfasten tens of bolts just to get to one little knock sensor that plugs in easily?”

Tools needed:

*A long extension for your socket wrench

*A wobble adapter

*A long pair of needle-nose pliers

*A long rather stiff wire or plumber’s snake

Procedure:

First disconnect the battery.

Disconnect two rubber fuel lines that block the space between the two middle intake runners and push aside (you may have to relieve some fuel pressure).

Disconnect the harness for the knock sensor, but before you go on, connect the plumber’s snake (or wire) to the end of the harness that leads to the sensor under the intake manifold.

Now unbolt the sensor.

Take the needle-nose pliers and reach down to pull out the sensor along with the wires (try not to pull out the entire length of plumber’s snake).

Disconnect the old sensor and plug in the new one.

NOW it gets tricky!! Go ahead and thread the bolt through the sensor before you lower it back into its place.

Wrap a thin piece of electrical tape around the head of the bolt as you insert it into the socket wrench, this helps keep the thing from slipping out of the socket as you lower everything back in.

As you steadily approach the engine block with sensor and bolt, pull out slack in wire with plumber’s snake in the direction of respective harness.

Bolt down the sensor and reconnect the harness.

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