Parts for your 2000 Toyota Bb-Temperature sensors

2000 Toyota bB temperature sensors — what they do and how to look after them

Temperature sensors are absolutely fitted to the 2000 Toyota bB (NCP30/NCP31/NCP35). Toyota’s own technical literature confirms this, including the Toyota bB Repair Manual for the NCP30 series (Engine Mechanical and EFI sections), the Electrical Wiring Diagram (EWD), and the 1NZ‑FE/2NZ‑FE Engine Control System manuals. These docs show the car uses multiple temperature sensors: the engine coolant temperature (ECT) sensor, intake air temperature (IAT) sensor—often integrated with the MAF on these models—plus A/C-related thermistors such as the ambient and evaporator sensors on vehicles with air conditioning.

On this bB, the ECT sensor is vital for cold starts, fuel metering, ignition timing, radiator fan control, and idle speed. The IAT helps the ECU trim fuelling based on air density. If fitted, the ambient and evaporator sensors help the A/C system manage cabin comfort and prevent evaporator freeze-up. When any of these go out of range, the ECU can default to a safe map, hurting performance and economy, or throw a check-engine light.

As part of servicing, it’s smart to check temperature sensor live data with a scan tool. After an overnight cold soak, ECT and IAT should read close to ambient and track sensibly as the engine warms. Inspect connectors for corrosion, broken tabs, and hardened loom tape, especially around the thermostat housing (ECT) and airbox/MAF (IAT). Coolant health matters, too—old coolant can encourage scale that affects the ECT’s thermal behaviour. Replace coolant per schedule (typically 160,000 km or 10 years for long-life red, then 80,000 km/5 years thereafter, or as specified for your exact coolant).

• Common symptoms of a dodgy ECT: hard cold starts, high idle, rich running, black smoke, poor fuel economy, radiator fans running oddly, and fault codes like P0115–P0119.
• IAT issues may cause sluggish response, lean/rich trims, or codes like P0110–P0113.
• When replacing, use a quality sensor and a new seal, for ECT, snug to spec on a cool engine and top up/bleed coolant properly.
• No coding is required, clear codes and confirm readings with a scan tool. An idle relearn may happen automatically after battery disconnect.
• Prevention: keep connectors clean, ensure the airbox and intake are sealed, and stick to coolant and filter service intervals.

Look after these small parts and the bB’s 1.3‑ or 1.5‑litre engine will start cleanly, run smoothly, and sip fuel the way it should across Kiwi and Aussie conditions.

Popular question: Where is the coolant temperature sensor on a 2000 Toyota bB?

It’s typically threaded into or near the thermostat housing on the cylinder head side of the engine. On the 1NZ‑FE/2NZ‑FE, look under the bonnet near the upper radiator hose outlet. You’ll see a two‑pin connector on the sensor body.

Popular question: Is the intake air temperature sensor separate or part of the MAF on this model?

On many 2000 bB variants, the IAT is integrated into the MAF sensor housing in the airbox/air intake duct. If the scan data shows an IAT fault, inspect and test the MAF/IAT assembly and its connector rather than looking for a separate IAT on the intake manifold.

Popular question: Do I need to drain coolant to change the ECT sensor?

Yes, in most cases expect some coolant loss. It’s best to work on a cold engine, partially drain the system to below the sensor level, swap the sensor and seal, then refill with the correct Toyota‑spec coolant and bleed out air. Always verify no leaks and confirm the ECT reading with a scan tool.