Parts for your 2009 Toyota Crown-Temperature sensors

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

Based on Toyota technical literature for the S200-series Crown (2008–2012), including the Toyota Repair Manual (Engine and Hybrid Control sections) and Electrical Wiring Diagram (EWD), as well as Denso NTC thermistor specifications commonly used by Toyota, the 2009 Toyota Crown is fitted with multiple temperature sensors. These are integral to engine, transmission, climate control and, on Hybrid variants, battery and inverter management.

Temperature sensors tell the car’s ECUs exactly how hot or cold key systems are so they can trim fuel, spark, idling speed, fan operation and A/C performance. If a sensor reads incorrectly, the engine can run rich or lean, shift quality can suffer, the A/C may misbehave, and fuel economy can go out the window. They’re small, inexpensive components that punch well above their weight in keeping a Crown running sweet as.

• Engine Coolant Temperature (ECT) — core input for fuelling, timing and fan control.
• Intake Air Temperature (IAT) — adjusts fuelling for air density.
• Automatic Transmission Fluid Temperature (TFT) — affects shift strategy and protection.
• Ambient and evaporator temp sensors — climate control accuracy and compressor protection.
• Hybrid variants: inverter and HV battery temp sensors — thermal management and longevity.

There’s no set replacement interval for these, they’re serviced on condition. As part of regular servicing, it’s smart to scan live data when the car is stone-cold: ECT and IAT should be close to ambient. After a run, confirm the ECT rises progressively and cooling fans cycle normally. Check connectors for green crusties, brittle boots, or coolant wicking up the loom, and ensure earths are clean and tight.

When an ECT or other sensor fails, you’ll often see a Check Engine Light with codes like P0115–P0119 (ECT) or P0110–P0113 (IAT), rough cold starts, high idle, or the temp gauge acting oddly. Replacement is straightforward: let the engine cool, relieve cooling system pressure, drain enough coolant to drop below the sensor, unplug, swap the sensor and seal/O-ring, and torque to the spec in the Toyota manual. Refill with Toyota Super Long Life Coolant (pink, premixed), bleed the system with the heater on hot, and verify live data and fan operation. For trans or A/C sensors, similar principles apply — access, replace, clear codes, and verify with a scan tool. Done right, the Crown will cruise happily for many more kilometres.

Popular questions

Where is the engine coolant temperature sensor on a 2009 Toyota Crown?
On GR-series V6 Crowns, the ECT sensor is typically threaded into the coolant outlet/thermostat housing near the upper radiator hose. It’s a two-pin sensor feeding the ECM. Some variants may also have a separate sender for the dash gauge. Access is usually from the top, remove intake ducting as needed and mind the harness clip.

What fault codes point to temperature sensor issues on this model?
Common codes include P0115–P0119 for ECT circuit/performance, P0125 or P0128 for coolant temperature/thermostat operation, P0110–P0113 for IAT, and P0711 for transmission fluid temperature. HVAC-related temp sensors may log B-codes in the A/C amplifier. Hybrid models can set thermal management codes if inverter or battery temps read out of range.

When should temperature sensors be replaced?
There’s no routine interval. Replace when diagnostics confirm a fault, readings don’t match reality (cold soak versus ambient), or the connector is oil/coolant-soaked or corroded. If a cooling system has suffered contamination or overheats, it’s reasonable to test the ECT and consider preventative replacement while you’re in there with fresh coolant and a new thermostat.