Location of knock sensor on a 1998 Saturn 4 cylinder

Here is a video showing how to change the knock sensor.

https://www.2carpros.com/questions/saturn-sl2-1999-saturn-sl2-how-to-change-a-knock-sensor

Here's a video on replacing your knock sensor. Nissan KA24DE Knock Sensor Remove install repair

you didn't state specific engine so here is a run down of locations
on a 4 cylinder engine there are 2 knock sensors located on the inlet side of the block adjacent to no 1 and 4 cylinders ( cross way motor)
on a v6 engine( crossway engine) they are in the valley of the block ( probably under the inlet manifold system) at 2 and 5 cylinder positions
on a v8 they will be located adjacent to 4 cylinder and between 6 and 8 cylinder on one side and adjacent to 3 cylinder and between 5 and 7 cylinder on the other side

Under the lower intake manifold.

It is on the lower left side of the engine (side towards firewall - see picture).
Knock sensor failures are pretty rare, why are you looking for it?

This engine has two knock sensors, one for ecah cylinder bank, both are located under the intake manifold, the manifold has to be removed to get to the sensors.

they will be on both side of the engine block and they thread in clockwise.

The knock sensor is on the rear of the motor behind the left cylinder head.Hope this helps.Good luck.

This engine does not use a cam sensor

1 - High Tension cable

• 4 to 8 Kohms
• With suppression connector and spark plug connector
• Only remove and install spark plug connector using tool T10029

2 - Ignition coil with output stage (-N70-, -N127-, -N291-, -N292-)
Connection, ignition wires:

• HV1 = Cylinder 1
• HV2 = Cylinder 2
• HV3 = Cylinder 3
• HV4 = Cylinder 4

3 - 10 Nm 4 - Connector

• 6 pin

5 - Knock sensor 1 -G61-*

• Contacts gold plated
• Fitting location: Cylinder block intake side

6 - 2-pin connector

• For knock sensor 1 -G61-
• Contacts gold plated
• Do not interchange

7 - Knock sensor 2 -G66-*

• Contacts gold plated
• Fitting location: Cylinder block intake side

8 - 2-pin connector

• For knock sensor 2 -G66-
• Contacts gold plated
• Do not interchange

9 - 20 Nm

• Tightening torque influences the function of the knock sensor

10 - Spark plug, 30 Nm

• Type and electrode gap See test data, spark plugs.
• Remove and install with 3122B

11 - Connector

• Contacts gold plated
• 3 pin

12 - 10 Nm 13 - 100 Nm

• Use counter- hold tool 3415 to loosen and tighten

14 - Camshaft sprocket

• With rotor for Camshaft Position (CMP) sensor

15 - Camshaft Position (CMP) sensor -G40-* 16 - Bracket

• For Camshaft Position (CMP) sensor