Parts for your 1992 Mitsubishi Pajero-Knock sensor

1992 Mitsubishi Pajero knock sensor — is it fitted, and what to do about it

Based on technical sources, a knock sensor is relevant to 1992 Mitsubishi Pajero petrol models but not to diesel variants. The Mitsubishi Pajero/Montero Factory Service Manual for the early second-generation (1991–1996) details a knock sensor input on the 6G72 3.0L V6 petrol engine for ignition timing control. The Mitsubishi ASA electronic parts catalogue lists a dedicated knock sensor for 6G72 petrol configurations, with no corresponding listing for the 4D56 2.5 TD or early 4M40 2.8 TD diesels. Industry manuals (e.g., Gregory’s/Haynes) and Mitsubishi OBD‑I diagnostic references also note a knock sensor circuit and fault code pathway for petrol models of this era, not for diesels.

Why diesels don’t use one on this Pajero: diesel combustion is controlled by fuel injection timing and the nature of compression ignition rather than spark advance, so the ECU doesn’t need a detonation feedback sensor to trim timing. The diesel injection system and mechanical design manage combustion noise and timing differently, making a traditional petrol-style knock sensor unnecessary on 1992 diesel Pajeros.

The petrol 6G72 Pajero does run a knock sensor, and it’s there to keep the V6 happy on Aussie and Kiwi fuels. It “listens” for detonation (pinging) and lets the ECU gently pull timing so the motor doesn’t rattle itself silly under load. That means smoother running, better reliability when towing or climbing, and a decent shot at good economy without risking piston or bearing damage. On this model, the sensor is mounted on the engine block in the V under the upper intake plenum, so it’s out of sight and usually forgotten until it plays up.

It’s not a regular service item, but it’s smart to deal with it when the upper plenum’s off for other jobs (like rocker cover gaskets, injector seals, or coolant crossover work). If there’s a ping under load, a Check Engine Light with an OBD‑I knock sensor code, or the Paj feels doughy because the ECU is pulling heaps of timing, it’s time to investigate. Use a quality OEM-equivalent sensor and don’t skimp on the harness — the wiring is shielded and sensitive to interference. Fit it to a clean, bare metal pad on the block, route the loom away from ignition leads, and torque it to factory spec, over‑tightening or using sealant can muffle the sensor and cause false readings.

• Common clues: pinging on hills, lazy performance, poor fuel use, CEL with a knock sensor/knock circuit code.
• Best practice: replace the intake/plenum gaskets, inspect the connector for brittleness, and avoid cheap no‑name sensors that can cause phantom knock.
• Verification: after fitting, clear codes and road‑test under load while monitoring timing retard with a suitable scan tool.

Referenced technical sources: Mitsubishi Pajero/Montero Factory Service Manual (1991–1996, 6G72 engine/engine electrical), Mitsubishi ASA Electronic Parts Catalogue (early Gen‑2 Pajero/Montero), Gregory’s/Haynes Pajero/Montero manuals, Mitsubishi OBD‑I diagnostic references noting knock sensor circuit for petrol variants.

Popular questions

Does my 1992 Pajero have a knock sensor?
Petrol 6G72 V6 models do, the ECU uses it to trim ignition timing. Diesel 4D56 and early 4M40 variants of the same year don’t have one, as their combustion control doesn’t rely on knock feedback.

Where is the knock sensor on the 3.0 V6 and how hard is it to replace?
It sits on the block in the V beneath the upper intake plenum. Replacement usually means pulling the plenum, so budget time for new gaskets and a careful reconnect of the shielded loom. It’s a doable driveway job for a competent spanner‑spinner.

Can a bad knock sensor hurt performance or fuel economy?
Yep. If the sensor or its wiring is dodgy, the ECU often retards timing to protect the engine, which makes the Paj feel flat and can chew more fuel. Sorting the sensor and harness typically restores pep and smoothness.