Mitsubishi Pick-ups and Montero 1983-1995 Repair Guide

Knock Sensor


The knock sensor is only found on 3.5L engines.


See Figure 1

The knock sensor converts cylinder block vibrations, due to knocking, into voltage signals. These signals are various voltages according to the strength of the knocking. These signals are input into the ECM. The ECM controls the delay in the spark timing according to these signals.

When knocking occurs when driving at maximum load, the following problems, other than the knock sensor, can be the cause: incorrect spark plug heat rating, incorrect gasoline, incorrect standard spark timing adjustment.

The knock sensor is located in the intake valley, under the intake.

Click image to see an enlarged view

Fig. Fig. 1: The location of the knock sensor in the intake manifold valley-3.5L engine


See Figure 2

  1. Unplug the knock sensor connector and the ECM harness connector. Check for an open or short-circuit to ground between the knock sensor terminal 1 and the ECM terminal 58. If a short or open-circuit does exist, repair the harness between the two terminals.
  3. Check for continuity from the knock sensor terminal 2 and ground. If there is no continuity, repair the terminal between the knock sensor terminal 2 and the ground.
  5. Plug all connectors back into their original components.

Click image to see an enlarged view

Fig. Fig. 2: The arrangement of the knock sensor connector terminals-3.5L engines


The knock sensor cannot be tested without an expensive scan tool from Mitsubishi. If the harness turns out all right and all other possible reasons for the malfunction have been investigated, take the vehicle to an automotive mechanic familiar with Mitsubishi vehicles.


To remove the knock sensor, the intake manifold plenum must be removed (refer to Engine & Engine Rebuilding for these procedures). When all components are removed, simply unscrew the knock sensor with an open or box wrench. Make sure not to damage the sensor.

To install the sensor, tighten the sensor into the engine until snug. Make sure not to crossthread the sensor into the engine. Install all of the components taken off of the engine for the sensor's removal.