Parts for your 2000 Toyota Echo|yaris-Temperature sensors

2000 Toyota Echo/Yaris Temperature Sensors

Temperature sensors are absolutely fitted to the 2000 Toyota Echo/Yaris (NCP10/NCP12, 1NZ‑FE). Toyota’s Factory Repair Manual (Engine Control System for 1NZ‑FE), the model-year Electrical Wiring Diagram (EWD), and the Toyota Electronic Parts Catalogue note the Engine Coolant Temperature (ECT) sensor and an Intake Air Temperature (IAT) sensor integrated into the mass-airflow (MAF) meter. These inputs are critical for fuelling, ignition timing, idle speed, radiator fan control, and the dash temperature display or warning logic.

On this Echo/Yaris, the ECT sensor threads into the coolant passage near the thermostat housing and tells the engine computer how hot the engine is. That info is used to richen mixtures on cold starts, stabilise idle, and switch the cooling fan. The IAT, housed in the MAF in the airbox ducting, helps the ECU fine‑tune fuelling as the day heats up or cools down. If either sensor goes out of range, the car can run rich, chew through petrol, start poorly when cold, or kick the fan on at odd times. Fault codes commonly logged include P0115–P0119 (ECT) and P0110–P0113 (IAT), as outlined in Toyota’s diagnostic sections.

There’s no fixed replacement interval in the factory schedule, but these sensors should be checked during servicing if any cooling or drivability quirks appear. A technician will usually verify live temperature readings with a scan tool and compare them to actual engine temp. If the ECT needs replacing, it’s straightforward: let the engine cool, relieve pressure, catch the coolant, unplug the connector, and swap the sensor, fitting a new sealing washer/O‑ring and tightening to the spec in the manual. Top up with the correct Toyota coolant and bleed air from the system. For the IAT/MAF, gentle cleaning with a MAF‑safe cleaner can restore accuracy—never touch the sensing element.

• Tell‑tale signs: hard cold starts, high idle, poor economy, temp gauge misbehaving, radiator fan running constantly, or a check‑engine light.
• Quick care tips: keep connectors clean and clipped firmly, inspect for coolant weeps at the sensor base, and use the right coolant when refilling.
• When in doubt, a scan of live data under the bonnet saves guesswork and parts.

Popular questions about 2000 Toyota Echo/Yaris temperature sensors

Where is the coolant temp sensor on a 2000 Echo/Yaris?
It’s mounted in the coolant passage near the thermostat housing on the 1NZ‑FE engine, typically on the engine side of the radiator hose outlet. Access is from the top with the airbox area clear. Look for a two‑pin connector on a small brass‑coloured sensor.

Can a dirty MAF/IAT cause rough running?
Yes. Because the IAT is built into the MAF, contamination can skew temperature and airflow readings, leading to rich or lean mixtures and a rough idle. Cleaning the MAF carefully with the correct spray often restores proper readings without replacement.

Does this model use a separate fan switch?
No. The radiator fan is commanded by the ECU using the ECT sensor’s signal, as shown in the Toyota EWD. There isn’t a standalone thermo‑switch, if the fan behaves oddly, an ECT or wiring check is a smart first step.