Parts for your 2004 Daihatsu Yrv-Temperature sensors

2004 Daihatsu YRV Temperature Sensors — What they do and how to look after them

Temperature sensors are absolutely relevant and fitted to the 2004 Daihatsu YRV. Technical references including the Daihatsu YRV Workshop Manual (2001–2005, Engine Control/EFI section), the Daihatsu Electronic Service Manual for K3-VE/K3-VET engines, and industry data sets such as Autodata/HaynesPro list an engine coolant temperature (ECT) sensor, an intake air temperature (IAT) sensor (integrated with the airflow or manifold system depending on variant), and an ambient temperature sensor used by the HVAC. These are core to engine and climate control on this model.

On the YRV, the ECT sensor feeds the ECU real-time coolant temperature so it can sort cold starts, fuel delivery, ignition timing and idle speed, and switch the radiator fans on when needed. It also helps drive the dash temperature gauge. The IAT sensor tells the ECU how warm the incoming air is, so it can fine-tune fuelling, on the turbo K3-VET it’s especially handy for boost control and knock protection. The ambient sensor lets the A/C system behave nicely on hot or frosty days so the cabin temp feels right.

When these sensors age or their connectors cop a hard life, owners can see rough cold starts, high fuel use, lazy throttle response, or fans running at odd times. A check engine light with codes like P0115–P0119 (ECT) or P0110 (IAT) can appear. Live-data on an OBD-II scanner is a quick way to sanity-check: a stone-cold engine should read close to outside temp, and once warmed up you’ll usually see around 80–95°C coolant temp on the YRV.

There’s no strict replacement interval, but it’s smart to inspect temperature-sensor wiring and plugs at each service. Keep coolant fresh and correct to spec—old or contaminated coolant can attack sensors from the inside. If the ECT fails or the reading’s unreliable, replace it with a quality OEM-equivalent part, fit the sealing washer/O-ring as supplied, and refill/bleed the cooling system carefully. Do the job on a cool engine and capture any old coolant for proper disposal. Avoid overtightening the sensor body.

• Common signs it’s time to act: hard cold starts, rich running, poor economy, erratic temp gauge, radiator fans stuck on or never coming on, or a CEL with ECT/IAT codes.
• Maintenance tip: for IATs built into the airflow meter, only use dedicated MAF cleaner—don’t touch the element.
• After replacement: clear fault codes, check for leaks, and confirm the fans cycle as expected once warm.

Backed by the Daihatsu factory literature and Denso EFI training material, these sensors are small parts that make a big difference to how well the 2004 YRV drives and how reliably it keeps its cool.

FAQs

Where is the engine coolant temperature sensor on a 2004 Daihatsu YRV?
It’s typically threaded into the thermostat housing or coolant outlet near the upper radiator hose, with a two-pin connector. On K3-VE/K3-VET engines it’s easy to spot once the engine cover is off. Always identify by connector and location before removal.

Is it okay to keep driving with a faulty temperature sensor?
It’ll usually run, but it’s not a great idea. The ECU may go into a limp strategy, fuelling can be off, fans may run at the wrong time, and there’s a risk of overheating or excess fuel use. Sort it sooner rather than later to protect the engine and wallet.

Do temperature sensors need programming after replacement?
No special programming is normally required. Fit the new sensor, refill and bleed coolant if applicable, then clear any fault codes. The ECU may trim itself over a short drive, just confirm stable temperatures and normal fan operation.