Parts for your 1999 Mitsubishi Pajero-Knock sensor

1999 Mitsubishi Pajero knock sensor — what’s fitted and why it matters

Based on technical sources, the 1999 Mitsubishi Pajero petrol models (6G72 3.0L and 6G74 3.5L V6) are fitted with a knock sensor, while the 2.8L turbo-diesel (4M40) is not. This is corroborated by the Mitsubishi Factory Service Manual for petrol engine management (which details knock sensor diagnostics including DTC P0325), the Mitsubishi ASA electronic parts catalogue for late Gen 2 Pajero (NL) V6 variants showing a block-mounted knock sensor, and Gregory’s/Gregory’s-Haynes workshop coverage for 1991–2002 Pajero petrol models. In contrast, the 4M40 Diesel Engine and Engine Electrical manuals list no knock sensor in the diesel control system.

For petrol Pajero owners, the knock sensor is a quiet achiever. It’s a piezoelectric microphone bolted to the V6 block (in the valley under the upper intake on most 6G7x engines). It “listens” for detonation (pinging) and lets the ECU trim ignition timing on the fly. That keeps performance crisp on 91–95 RON fuel, helps fuel economy, and protects the engine under load or on hot days towing up the Kaimais or the Great Dividing Range.

Service-wise, the knock sensor itself isn’t a regular replacement item, but it should be considered during major intake work or if the MIL pops up with P0325/P0330, rough running, flat spots, or stubborn pinging. Common culprits are heat-hardened wiring in the valley, oil contamination, or cracked sensor housings. If it’s crook, timing gets pulled back and the Pajero can feel lazy and drink more fuel.

• Inspection tips: look for brittle or oil-soaked loom, loose or corroded mounting, and poor connector fit.
• Replacement notes: access typically needs the upper intake removed. Fit an OEM-quality sensor, seat it on a clean, dry boss, and tighten to factory torque. Don’t use sealants or thread tape.
• Good practice: keep cooling system tidy, run decent fuel, and sort vacuum leaks—these all help the sensor do its job.

Why diesel models don’t use one: the 4M40 is compression-ignition and naturally “noisier,” so a conventional spark knock sensor isn’t part of its control strategy. Injection timing is managed by the ECU and pump using crank/cam signals, boost, temp and fuel system feedback—not knock detection.

Signs the V6 knock sensor circuit needs attention include persistent P0325, poor throttle response, higher-than-normal consumption, and pinging that doesn’t ease with better fuel. A quick scan with MUT-II/OBD-II, a wiring check, and confirming proper sensor torque usually sorts the diagnosis without guesswork.

Popular questions

Where is the knock sensor on a 1999 Pajero V6?
On most 6G72/6G74 engines it’s a single sensor bolted to the top of the engine block in the V valley, typically beneath the upper intake manifold. That means intake removal for proper access. Trace the sub-loom running through the valley to spot it.

Can a faulty knock sensor harm the engine?
Indirectly, yes. The ECU will usually pull timing to keep things safe, so you’ll feel a power drop and see higher fuel use. If the wiring is intermittent, you can still get pinging under load. Leaving it unchecked risks long-term stress, fix the wiring or sensor and restore proper timing control.

Does the 2.8 diesel Pajero have a knock sensor?
No. The 4M40 diesel uses compression ignition and a different control strategy, so it doesn’t rely on a spark knock sensor. If it’s rattly or down on power, look to injectors, pump timing, boost or air leaks instead.