Parts for your 2009 Subaru Tribeca-Temperature sensors

2009 Subaru Tribeca temperature sensors — what they do and how to look after them

Temperature sensors are absolutely used on the 2009 Subaru Tribeca (EZ36 3.6‑litre H6). Subaru’s factory service manuals for the 2009 Tribeca list the Engine Coolant Temperature (ECT) sensor as a key input to the engine control module, with diagnostics for DTCs P0115–P0119 and P0125. The 5EAT automatic transmission section documents an ATF temperature sensor (e.g., DTC P0711/P0713). HVAC wiring diagrams show an ambient air temperature sensor at the grille and an evaporator temperature sensor for the air‑con. These match standard OBD‑II behaviour (SAE J1979 Mode 01 PID 05 for coolant temp), confirming temperature sensors are integral to this model’s operation.

On a 2009 Tribeca, temperature sensors do a stack of behind‑the‑scenes work. The ECT sensor helps the ECU manage cold starts, fueling, ignition timing, radiator fan operation and the dash gauge. The intake air temperature reading (integrated with the airflow meter on this model) fine‑tunes mixture as air density changes. The transmission fluid temp sensor protects the 5EAT by adjusting shift strategy and warning if things get too hot. For comfort, the ambient and evaporator sensors guide the climate control so the air‑con doesn’t freeze the evaporator or blow the wrong temp on a frosty morning.

As part of regular servicing, it’s smart to give these sensors and their wiring a quick once‑over. Look for cracked connectors, green corrosion, brittle loom tape near heat sources, and coolant weep around the ECT boss. If removing the ECT sensor, only do it on a stone‑cold engine and be ready to bleed the cooling system after refit. Use the correct spec coolant and keep change intervals per Subaru’s schedule, poor coolant can foul sensors and skew readings.

• When replacing, choose quality OE or equivalent parts, fit a new sealing washer/O‑ring where applicable, and avoid thread sealants that can insulate the sensor’s tip.
• Don’t over‑tighten into alloy housings under the bonnet — follow torque guidance from the Subaru manual.
• After replacement, clear fault codes and verify live data (ECT, IAT, ATF temp) with a scan tool, watch that the radiator fans cycle normally as the engine warms.

Common signs of a dodgy temperature sensor include hard cold starts, rich fuel use, radiator fans running constantly, erratic temp gauge, air‑con cutting out early, or transmission shifting oddly when hot. Sorting a lazy sensor early can save fuel, protect the 5EAT, and keep the Tribeca happy on long Kiwi or Aussie runs.

Popular questions

Where is the coolant temperature sensor on a 2009 Tribeca?
The ECT sensor sits threaded into the coolant passage near the thermostat housing on the front of the EZ36, beneath the plastic engine cover. It reads coolant temperature directly from the engine and feeds that to the ECU and the cluster.

Access usually involves removing the engine cover and some intake ducting. Always work with the engine cold and be prepared to catch a small amount of coolant.

What symptoms point to a failing ECT sensor?
Expect rough or rich cold starts, higher than normal fuel use, a temp gauge that behaves oddly, radiator fans that run at the wrong times, or a check engine light with codes like P0115–P0119 or P0125.

A scan tool is the quickest check: compare the ECT value to ambient on a cold engine. If it’s way off, wiring or the sensor itself may be at fault.

Does the Tribeca have an ambient temperature sensor for the air‑con?
Yes. There’s an ambient air temperature sensor mounted forward in the grille area, and an evaporator temperature sensor in the HVAC box. They help the climate control system hit the set temperature and prevent evaporator icing.

If the outside temperature reading is nonsense or the air‑con cycles strangely, inspect the ambient sensor and its connector for damage or corrosion.