Parts for your 2011 Toyota Vitz|yaris-Temperature sensors

2011 Toyota Vitz/Yaris temperature sensors: what they do and when to service them

On the 2011 Toyota Vitz/Yaris, temperature sensors aren’t just relevant — they’re essential. Toyota’s service manuals and wiring diagrams for the XP130 series list an Engine Coolant Temperature (ECT) sensor and an Intake Air Temperature (IAT) sensor (typically integrated into the MAF on most trims). The factory diagnostic code sets include P0115–P0119 (ECT circuit) and P0110–P0113 (IAT circuit), confirming the ECU relies on these. Many variants also use an ambient air temp sensor for the A/C and outside temp display, an evaporator temp sensor for anti-icing, and a transmission/CVT fluid temperature sensor to protect the driveline and refine shift strategy. Parts catalogues for this model family show these sensors across common engines like 1KR-FE and 1NR-FE.

The ECT sensor feeds the ECU with coolant temperature so it can sort cold-start enrichment, ignition timing, idle speed, radiator fan operation, and closed-loop readiness. If it reads off, the engine can run rich, surge at idle, or keep the fans on when it’s not needed. The IAT sensor helps the ECU account for air density changes, sharpening fuelling and throttle response from a frosty morning in Dunedin to a hot arvo in Darwin. Where fitted, the transmission/CVT fluid temp sensor protects the box under heavy loads and summer heat, while the ambient and evaporator sensors keep the cabin comfy and prevent evaporator icing.

There’s no fixed replacement interval for these sensors, Toyota treats them as monitor-and-replace-on-condition items. That said, a 2011 vehicle is now well into the age where connectors, seals, and plastics can get brittle. As part of routine servicing, it’s smart to:

• Scan live data cold and hot. ECT should track ambient when stone-cold and cruise to ~85–95°C when fully warm, IAT should be near ambient with the engine off.
• Check for DTCs like P0115/P0117/P0118 (ECT) or P0110/P0112/P0113 (IAT), and inspect connectors for corrosion or oil wicking.
• Verify wiring integrity and grounds before blaming the sensor.

When replacing the ECT sensor, work on a cool engine, depressurise the cooling system, and catch any spill. Use a deep socket, fit a new O-ring or washer as specified, and avoid thread sealant unless the manual calls for it. Refill with Toyota Super Long Life Coolant (pink), bleed air properly, and recheck for leaks. IAT/MAF units typically use a simple clip or screws, fit an OE-quality part (often Denso) and avoid over-oiling air filters that can foul the element. Transmission temp sensors may be integrated into the internal harness on some CVT models, so diagnosis before parts ordering is wise.

Tell-tale signs of a crook temp sensor include hard cold starts, high idle after warm-up, poor fuel economy, black exhaust smoke, a lazy temp gauge or fans running constantly, and A/C cutting in and out. A quick scan and a couple of resistance checks against the workshop manual specs usually nail it.

Where is the engine coolant temperature sensor on a 2011 Vitz/Yaris?

On most 1KR-FE and 1NR-FE engines found in the 2011 Vitz/Yaris, the ECT sensor is threaded into the coolant outlet/housing at the cylinder head end, near the thermostat area. It’s a two-wire sensor with a plastic connector and sits under the bonnet on the transmission side of the head on many trims.

Access is typically straightforward with a deep socket once the engine is cool. Expect a small coolant loss on removal, have a tray and fresh Toyota SLLC ready.

What symptoms point to a failing ECT sensor on this model?

Common giveaways are hard cold starts, rich running, rough idle after warm-up, the radiator fan running almost constantly, and poor fuel economy. The check engine light may set codes like P0115, P0117 or P0118.

Live data that shows a wildly low or high temperature compared with actual engine condition is another clue. Confirm with wiring checks before replacing the sensor.

Does the 2011 Vitz/Yaris have an intake air temperature sensor separate from the MAF?

Most 2011 Vitz/Yaris variants use an IAT element integrated into the MAF housing on the airbox intake. The ECU reads air temperature and mass flow from the same assembly.

Some market/engine combos can place the IAT separately in the intake duct, but that’s less common on this generation. If replacing, match the part to the VIN or engine code to avoid fitment mix-ups.