Parts for your 2002 Mitsubishi Pajero-Temperature sensors

2002 Mitsubishi Pajero Temperature Sensors — What They Do and When to Replace

Temperature sensors are absolutely fitted to the 2002 Mitsubishi Pajero (NM/NP), and they’re central to how the engine and driveline behave. Mitsubishi’s Pajero/Montero NM–NP Workshop Manual (2000–2006) details an engine coolant temperature (ECT) sensor and intake air temperature (IAT) sensor for both the 3.2 Di‑D diesel (4M41) and 3.5 V6 petrol (6G74). The auto trans models also use an ATF temp sensor, and the HVAC system uses ambient and evaporator thermistors. OBD‑II diagnostics (SAE J1979) back this up with fault codes like P0115–P0119 for ECT and P0110–P0113 for IAT.

On this Pajero, the ECT sensor is the MVP. It tells the ECU how hot the engine is so it can set fuel, timing, idle speed, glow plug strategy on the diesel, and switch the radiator fans as designed. The IAT helps fine‑tune fueling as air temps swing from frosty mornings to scorching arvos. Auto transmissions rely on fluid temp to manage shift timing and torque converter lock‑up. HVAC temp sensors prevent evaporator icing and keep cabin temps comfy.

Typical signs a temp sensor is on the way out include:

• Hard cold starts, rough idle, or over‑rich running
• High fuel use and sluggish performance
• Radiator fans running at odd times or not at all
• Temp gauge misbehaving (note: the dash gauge often has its own sender)
• Check Engine Light with ECT/IAT codes

As part of regular servicing, it’s worth a quick health check every 40,000–60,000 km:

1. Scan live data when cold and at full operating temp. Look for realistic readings and smooth change as it warms up.
2. Inspect connectors for coolant wicking, corrosion, or broken tabs. Clean and reseat.
3. Keep the cooling system mint: fresh coolant at the right mix, no air pockets, tidy hoses. A sick cooling system can make a good sensor look bad.
4. If readings are jumpy or out of spec, replace the sensor and sealing washer/O‑ring. Work on a cold engine, catch a little coolant, and tighten to the workshop manual spec.

There’s no fixed replacement interval for ECT or IAT sensors, but by 20‑plus years they’re fair game. If chasing fuel economy gremlins, fluctuating temps, or repeated DTCs, a new quality sensor is often cheap insurance. After replacement, clear codes and confirm fans, cold start, and warm‑up behaviour are spot on with a road test.

Popular questions about 2002 Mitsubishi Pajero temperature sensors

Where is the engine coolant temperature (ECT) sensor located?
On most 2002 Pajero engines, the ECT threads into the thermostat housing or upper coolant outlet on the engine. It’s a two‑pin sensor with a plastic connector. Access is usually from the top, disconnect the plug and look for a small brass/steel body sitting in coolant flow.

Can a faulty temperature sensor cause poor fuel economy?
Yes. If the ECT reads colder than reality, the ECU enriches the mix as if on warm‑up, burning more fuel and washing cylinder walls. Incorrect IAT readings can skew fuelling too. A quick scan of live data against an actual cold start temp is the fastest way to spot it.

Does the diesel 3.2 Di‑D have more than one temp sensor?
Yes. The 4M41 diesel uses an ECT for the ECU plus a separate sender for the dash gauge on many variants. The auto trans has its own ATF temp sensor, and the HVAC system uses evaporator/ambient sensors. Each plays a different role, so one failing doesn’t automatically condemn the others.