Parts for your 2009 Toyota Blade-Temperature sensors

2009 Toyota Blade temperature sensors — what they do and how to look after them

Temperature sensors are absolutely fitted to the 2009 Toyota Blade and are central to how it runs. Technical documentation for the E150-series platform and Blade models — including Toyota’s Repair Manual for Corolla/Auris/Blade (Engine Control System sections for 2AZ‑FE and 2GR‑FE), Toyota Electrical Wiring Diagram (EWD), and DENSO sensor specifications — all describe the engine coolant temperature (ECT) sensor, intake air temperature (IAT) sensing, ambient air temperature sensor for HVAC, and automatic transmission fluid (ATF) temperature sensing. Those sources confirm these sensors inform the engine ECU, transmission control, instrument cluster and climate control.

On both the 2.4‑litre 2AZ‑FE and the 3.5‑litre 2GR‑FE Blade/Blade Master, the ECT sensor tells the ECU how warm the engine is so it can manage cold starts, idle speed, fuel and ignition timing, fan operation and VVT‑i strategies. The IAT reading, typically built into the MAF sensor on the air box, trims fuelling and spark for air density. The ambient temp sensor behind the grille keeps the climate control honest, while the ATF temp sensor in the auto trans helps select shift timing and line pressure. That’s why a crook reading can cause rough cold starts, poor economy, lazy shifts or fans running when they shouldn’t.

They’re not a scheduled replacement item, but they do like a bit of care during regular servicing:

• Check scan data with a proper tool: cold ECT/IAT should match outside temp, fully warm ECT typically sits around the low‑90s °C. Oddball numbers or sudden spikes suggest trouble.
• Inspect connectors and earths under the bonnet — heat and age can make plastics brittle and pins corrode.
• Use the correct Toyota Super Long Life Coolant, poor coolant can foul the ECT sensor and skew readings.
• Keep the MAF/IAT clean with MAF‑safe cleaner (never carb/brake cleaner).

Replacing the ECT sensor? It’s mounted at the water outlet/thermostat housing on these engines. Safely relieve pressure, drain a little coolant, swap the sensor with a quality OEM‑equivalent (DENSO is the OE), fit a new seal, torque to the spec in the Toyota manual and bleed the cooling system. The IAT is integrated with the MAF on most Blades, replace as an assembly if the thermistor’s failed. The ambient sensor clips in behind the front bumper/grille — make sure it’s not dangling in hot engine bay air after panel repairs. ATF temperature sensors live inside the transmission valve body, so diagnosis is via scan data and the fix involves transmission work if it’s actually faulty.

Authoritative sources: Toyota Service Information/Repair Manual for E150 Corolla/Auris/Blade (Engine Control and Cooling sections), Toyota EWD for Blade, and DENSO temperature sensor specifications used by Toyota.

Popular questions

Where is the coolant temperature sensor on a 2009 Toyota Blade?
It’s fitted at the water outlet/thermostat housing on the engine, accessible from the top on most cars. Expect some coolant loss when removing it. On both the 2AZ‑FE and 2GR‑FE, access improves if the intake ducting is moved aside. Always confirm placement with the Toyota Repair Manual for your exact VIN.

Does the Blade have a separate intake air temperature sensor?
Yes — the IAT is typically integrated into the MAF sensor on the air box snorkel. If the IAT reading is off, try cleaning the MAF carefully with MAF cleaner. If it’s still out of range or throwing a code, replace the MAF assembly with a quality unit.

What temps should I see on a scan tool?
On a cold start, ECT and IAT should be close to ambient. Fully warmed up after a normal drive, ECT commonly sits around 85–95 °C, with fans kicking in higher as mapped by the ECU. IAT will usually trail slightly above ambient when moving, and climb at idle. Always compare with the specs in Toyota’s service data.