Parts for your 1990 Mitsubishi Pajero-Temperature sensors

1990 Mitsubishi Pajero temperature sensors

Temperature sensors are absolutely fitted to the 1990 Mitsubishi Pajero. Factory references including the Mitsubishi Pajero/Montero 1983–1993 Workshop Manual (Engine and Electrical), the Mitsubishi ECI‑MULTI EFI training material, the 4D56 diesel engine manual, and the Haynes Montero/Pajero 1983–1999 guide all detail coolant temperature sensors for the engine control unit on EFI petrol models, separate senders for the dash gauge, and additional temperature switches/sensors used for glow plug control on diesels and for cooling fan or air‑con functions on some trims.

In this era Pajero, temperature sensors do a heap of quiet, critical work. On petrol EFI models (like the 6G72 V6), the engine coolant temperature (ECT) sensor tells the ECU how warm the engine is, so it can sort out cold‑start enrichment, idle speed and ignition timing. There’s usually a separate single‑wire sender for the dash gauge. On 4D56 diesels, a coolant sender feeds the gauge and a temp input helps the glow plug controller. Many vehicles also use a thermo switch or sensor to trigger the radiator or condenser fans, and auto transmissions can have a fluid temperature sensor inside the box for shift protection. If any of these go off song, you’ll see hard cold starts, rich running, poor fuel use, erratic idle, or a gauge that reads oddly. Fans that never come on (or never switch off) are another giveaway.

Replacement isn’t hard if you take a careful, by‑the‑book approach. Work with the engine cold, crack the radiator cap to release pressure, and drain a litre or two of coolant so you’re not wearing it. Identify the right part: the ECU’s ECT is typically a two‑pin sensor near the thermostat housing, the gauge sender is a separate single‑pin unit. Diesels place these on or near the thermostat outlet too. Fit the correct sensor for your engine code, use a new sealing washer or thread sealant only if the manual calls for it, and tighten to the workshop spec—snug, not gorilla tight. Refill with quality coolant, bleed out air, and verify fan operation and gauge behaviour. While you’re there, check the connectors for green crust or loose pins and tidy any heat‑baked loom tape. There’s no set replacement interval, but given the age, testing resistance against the factory temp chart or proactively renewing a dodgy sensor during a cooling‑system service (every couple of years) is smart, especially before heading bush.

• Common symptoms: hard starting, rich/lean running, surging idle, poor economy, odd gauge readings, fans misbehaving.
• Good practice: use OEM‑quality sensors, follow torque specs, and refresh coolant and sealing washers.

Popular questions

How many temperature sensors does a 1990 Pajero have?
It depends on engine and trim. Petrol EFI models typically have a two‑pin ECT for the ECU and a separate single‑pin sender for the dash gauge, plus a thermo switch/sensor for the fan. Diesels have a gauge sender and a temperature input for the glow system. Auto transmissions may include an internal ATF temperature sensor.

Where is the coolant temperature sensor located?
On most 1990 Pajeros it’s near the thermostat housing. The 6G72 V6 usually places the ECU’s ECT on the intake manifold side by the thermostat outlet, while the 4D56 diesel mounts its temp units on or near the thermostat housing at the front of the engine. The gauge sender is nearby but uses a single wire.

Can you drive with a faulty temperature sensor?
You can, but it’s not wise. The ECU may over‑fuel or under‑fuel, causing rough running and higher consumption, and fans may not behave correctly, risking overheating. For diesels, glow timing can be off, making cold starts painful. Best to test and replace before a long trip.