Parts for your 2013 Toyota Bb-Temperature sensors

2013 Toyota bB temperature sensors — what they do and how to look after them

Temperature sensors are absolutely used on the 2013 Toyota bB. Toyota’s Repair Manual (RM) and New Car Features (NCF) for the QNC20/QNC21 bB, along with the Toyota Electronic Parts Catalogue, list several: an Engine Coolant Temperature (ECT) sensor, an Intake Air Temperature (IAT) sensor element integrated in the MAF, an ambient air temperature sensor for the climate control/external display, and an automatic transmission fluid (ATF) temperature sensor on auto models. These are core inputs the ECM and HVAC systems rely on for proper running and comfort.

Their job is straightforward but vital. The ECT sensor tells the engine computer how warm the coolant is, so it can sort cold-start fuelling, idle speed, ignition timing and when to kick the radiator fans on. It also helps protect the engine by pulling back power or switching off the A/C if things get too hot. The IAT sensor lets the ECM trim fuelling based on the temperature and density of incoming air, helping economy and smooth response. The ambient sensor feeds the climate control so it can keep the cabin comfy and keep the outside temp display honest. On autos, the ATF temp sensor helps the transmission decide shift timing and converter lock-up, especially on cold mornings or under load.

They’re not a regular “service item” like oil or filters, but they do benefit from a bit of care. If the bB shows hard cold starts, a high idle that won’t settle, the fans running all the time, rich running, poor economy, or weird A/C behaviour, it’s worth checking temp sensor data with a scan tool and inspecting connectors for corrosion or broken clips. Keeping fresh, correct coolant in the system helps the ECT live a long life. Cleaning the MAF (with proper MAF cleaner) can restore accurate IAT readings.

• When replacing the ECT: work on a cold engine, relieve system pressure, drain a little coolant, swap the sensor with a new seal, then refill and bleed the cooling system.
• Use quality OEM-equivalent parts (many are DENSO on Toyota) and avoid overtightening, a snug, sealed fit is the goal.
• After any sensor replacement, verify readings with a scan tool: cold ECT and IAT should be close to ambient, warm ECT typically sits around 85–95°C in normal driving.

There’s no fixed replacement interval. Many workshops simply test them during diagnostics or at high kilometres (say, 150,000+ km) or whenever cooling or intake work is being done.

Popular questions about 2013 Toyota bB temperature sensors

Where is the engine coolant temperature sensor located?
On most 2013 bB models with the 1NZ-FE/2NZ-FE engines, the ECT sensor sits near the thermostat housing/coolant outlet at the front of the engine. It’s a two‑pin sensor threaded into the coolant passage. Access is usually from the top with the bonnet up, allow the engine to cool before unplugging it.

What fault codes point to a bad temperature sensor?
Common ECT-related codes include P0115–P0119. IAT issues often show as P0110–P0114. Ambient temperature sensor faults can set HVAC-related body codes, and autos with temp-signal issues may throw shift-performance or temp-sensor codes. Always check live data before replacing parts.

Do temperature sensors need routine replacement?
No scheduled replacement is specified. Replace only when tests show they’re out of spec or when there are clear symptoms. Good coolant maintenance, clean connectors and a healthy MAF go a long way to keeping the sensors accurate for the long haul.