Parts for your 2017 Toyota Avensis-Temperature sensors

2017 Toyota Avensis temperature sensors — what they do and how to look after them

Temperature sensors are absolutely fitted to the 2017 Toyota Avensis. Technical sources such as the Toyota Avensis (T27) Repair Manual for the 2015–2018 model update, Toyota’s Electrical Wiring Diagram (EWD) set, and the Toyota Electronic Parts Catalogue confirm multiple temperature sensing devices across engine, transmission and HVAC systems. OBD-II standards (ISO 15031/SAE J1979) used by this model also define diagnostics for these sensors, so they’re very much part of the car’s control strategy.

On this Avensis, temperature sensors help the ECU and other control modules decide fuel delivery, ignition timing, idle speed, fan operation and more. They’re key to smooth cold starts, good fuel economy, emissions control, comfort inside the cabin and, on diesel models, DPF regeneration. If one goes out of range, the car can default to rich mixtures, run the radiator fans flat-out, or drop into limp mode.

• Engine Coolant Temperature (ECT) sensor – manages warm-up, fans and gauge/warnings.
• Intake Air Temperature (IAT) sensor – usually integrated with the MAF, trims fuel and spark.
• Ambient/outside air temp sensor – feeds the HVAC and dash reading.
• Automatic/CVT transmission fluid temperature sensor – influences shift strategy and protection.
• Diesel models: exhaust gas temperature (EGT) and DPF temperature sensors – control regeneration and protect the turbo/aftertreatment.
• A/C evaporator temperature sensor – prevents evaporator icing and stabilises cabin temp.

As part of regular servicing (typically every 12 months or 15,000 kilometres), it’s smart to scan live data and check for stored codes, inspect connectors under the bonnet for corrosion or broken tabs, and ensure the cooling system is healthy. Fresh, correct Toyota coolant helps the ECT sensor read accurately and prevents scale on the sensor tip.

There’s no routine replacement interval for these sensors, replace on fault or damage. Common signs include hard cold starts, fans running constantly, a stubborn high idle, poor fuel use, erratic outside-temp readings, frequent DPF regens (diesel) or a check engine light. Typical fault codes include P0115–P0119 (ECT), P0110–P0114 (IAT), P0070–P0073 (ambient), P0711 (ATF temp) and P242A/P242B (EGT/DPF temp).

When replacing, use quality OEM-spec parts. For an ECT sensor, let the engine cool, relieve system pressure, and fit a new sealing washer, refill and bleed coolant properly. For IAT integrated in the MAF, replace the assembly and only clean with MAF-safe cleaner. EGT sensors can seize in place—use penetrating oil and the correct socket to avoid twisting the harness. After any sensor work, clear codes and verify normal readings on a scan tool during a road test.

Where is the engine coolant temperature sensor located on a 2017 Avensis?

On most petrol variants it’s fitted near the thermostat housing or water outlet on the cylinder head, on D-4D diesels it’s typically at the water outlet assembly. Exact placement varies by engine code, so checking the Toyota Repair Manual or EWD for the specific engine is the best way to pinpoint it quickly.

Will a faulty temperature sensor turn on the check engine light?

Yes. The ECU monitors plausibility and range for each sensor. Expect codes such as P0115–P0119 (ECT), P0110–P0114 (IAT), P0070–P0073 (ambient), P0711 (ATF temp) or P242A/P242B (EGT/DPF temp). The car may also show symptoms like high fan speed, rich running, or limp mode (especially on diesels).

Do temperature sensors need preventative replacement?

Not usually. They’re replaced on condition. Preventative care means keeping coolant fresh, ensuring good engine grounds, protecting connectors from moisture and scanning the car at each major service to spot a drifting sensor before it causes headaches.