Parts for your 1993 Mitsubishi Pajero-Knock sensor

1993 Mitsubishi Pajero knock sensor — what’s fitted, what’s not, and how to look after it

Based on Mitsubishi factory references, whether a 1993 Pajero uses a knock sensor depends on the engine. The Mitsubishi Pajero/Montero 1991–1996 Factory Service Manual (Engine Control/EFI), along with the Mitsubishi ASA/CAPS electronic parts catalogue, shows a block-mounted knock sensor on EFI petrol V6 engines (notably the 6G72). The diesel engine wiring and engine control diagrams in the same FSM sets (4D56 and 4M40) do not include a knock sensor, and earlier carburetted petrol setups lack it as well.

• Petrol EFI V6 (6G72, some 6G74 markets): Knock sensor fitted and used by the ECU.
• Diesel (4D56 2.5, 4M40 2.8): No knock sensor used.
• Carburetted petrol variants: No knock sensor used.

For 1993 Pajeros running the EFI V6, the knock sensor is a quiet workhorse. Mounted to the engine block in the V of the cylinders under the intake, it listens for high-frequency vibration caused by detonation (pinging). When it detects knock, it signals the ECU to trim ignition timing and, if needed, enrich fuel delivery, keeping the engine safe on hot days, under load, or when fuel quality isn’t ideal. That clever closed-loop control lets the V6 hold decent performance without risking piston or bearing damage. Owners typically won’t notice it working, they only notice when it doesn’t.

Symptoms of a lazy or failed knock sensor include a check-engine light, flat performance, roughness under load, increased fuel use, or persistent pinging. Because the ECU errs on the safe side, the engine may feel doughy as timing is pulled back. A proper scan (even on OBD1) and a basic wiring check usually tell the story. Oil or coolant leaks into the valley can soak the connector and shielded lead, so loom condition matters just as much as the sensor itself.

Replacement on the 6G72 usually means removing the upper intake plenum to reach the sensor on the block. It’s not a frequent service item, but it’s smart to inspect it any time the intake is off. Fit an OEM-quality unit, keep the mating face clean and dry, and tighten to the factory torque spec—over- or under-tightening affects sensitivity. Avoid sealants unless the FSM calls for them. While there, tidy the harness routing and shielding, and sort any weeps that could contaminate the area. Treated right, a new sensor should last for years and thousands of kilometres of trouble-free touring.

For diesels in the 1993 Pajero line-up, a knock sensor isn’t used because diesel combustion is controlled by injection timing and pressure rather than spark. The characteristic diesel “knock” isn’t the same detonation event petrol ECUs are designed to catch, so the FSM’s diesel control systems omit a knock sensor entirely.

Popular questions

Where is the knock sensor on a 1993 Pajero V6?
On EFI V6 models (6G72), it’s mounted to the top of the engine block in the V between the cylinder banks, beneath the intake plenum. Access typically requires removing the upper plenum, so many technicians tackle it while doing intake gaskets or rocker cover work.

What are the signs a Pajero knock sensor has failed?
Common signs include a check-engine light, lacklustre acceleration, poor fuel economy, and sometimes audible pinging under load. The ECU may heavily retard timing to protect the engine, making the vehicle feel sluggish. Inspect the sensor’s connector and shielded wire for oil/coolant contamination before condemning the sensor.

Does a 1993 Pajero diesel have a knock sensor?
No. The 4D56 2.5 and 4M40 2.8 diesels use mechanical/electronic fuel injection control without a spark system, so there’s no petrol-style knock sensing in the FSM diagrams for those engines.