Parts for your 2006 Toyota Prius-Temperature sensors

2006 Toyota Prius temperature sensors: what they do and how to look after them

Technical sources including Toyota’s New Car Features manual (NCF) for the XW20 Prius, the Toyota Repair Manual available via Toyota TIS, and the 2006 Prius Electrical Wiring Diagram (EWD) all confirm that the 2006 Toyota Prius is fitted with multiple temperature sensors. These include the engine coolant temperature (ECT) sensor, inverter/converter coolant temperature sensing, high-voltage (HV) battery temperature sensors (a set of thermistors), intake air temperature (within the MAF), and an ambient air temperature sensor for climate and engine control. So temperature sensors aren’t just relevant on this model—they’re essential to how the hybrid system runs and protects itself.

On a 2006 Prius, temperature sensors are the quiet achievers. The ECT sensor tells the engine ECU how warm the engine is so it can trim fuel, ignition timing, and idle, control VVT-i behaviour, and switch the radiator fans. The inverter/converter’s temperature feedback helps the hybrid control keep the power electronics cool and safeguard the motor-generators. In the rear, the HV battery pack uses multiple temperature sensors to manage its cooling fan and to prevent the pack from getting too hot under load. Intake and ambient air temperature readings round out the picture for accurate fuelling and comfortable climate control.

They’re not a scheduled “change-out” item, but they do deserve attention during servicing. Good practice includes:

• Scanning live data to confirm sensible readings for ECT, inverter, and HV battery temps—handy for spotting a lazy sensor early.
• Refreshing coolant on time and verifying the inverter coolant pump is circulating, Gen 2 pumps are known wear items.
• Keeping the HV battery cooling ducting and fan clean, especially if the car does lots of city or dusty driving.
• Checking connectors and harnesses under the bonnet and near the battery for corrosion or damage.

When a sensor does fail, the car will usually tell on itself—think hard cold starts, fans running unexpectedly, poor fuel economy, the red triangle, or DTCs like P0117/P0118 (ECT circuit) or P0A93 (inverter cooling performance). Replacement is straightforward for most items: use quality OEM-equivalent sensors, avoid thread sealants that can insulate thermistors, torque to spec, and bleed both the engine and inverter coolant loops properly. After fitting, validate with live data so the temps look plausible across a warm-up cycle. A little preventative care here saves headaches, keeps the hybrid gear happy, and helps the Prius sip fuel the way it should.

• Typical signs a temp sensor system needs attention:
  • Overheating warnings or inverter pump not moving coolant
  • Battery fan running loudly or frequently
  • Erratic gauge behaviour, poor economy, or rough cold running

Popular questions about 2006 Toyota Prius temperature sensors

Where are the main temperature sensors located on a 2006 Prius?
The ECT sensor sits on the engine’s coolant outlet area. The inverter/converter temperature sensing is integrated within the inverter cooling circuit under the bonnet. The HV battery temperature sensors are mounted within the battery pack under the rear seat/boot floor area. Intake air temperature is part of the MAF on the intake tube, and the ambient sensor is up front behind the bumper/grille.

Do temperature sensors need regular replacement?
Not usually. They’re monitored by the ECUs and replaced on condition. During service, check live data, confirm both coolant loops circulate properly, and keep the HV battery fan and ducting clean. Replace any sensor that flags a fault, gives implausible readings, or shows wiring/connector damage.

What should be checked if P0A93 or inverter overheating is reported?
Start by confirming the inverter coolant pump runs and that you can see fluid movement in the reservoir. Inspect coolant level and condition, look for blockages in the inverter radiator, and check for air pockets after any cooling system work. If temps still spike, investigate sensor feedback and wiring per the Toyota Repair Manual flowcharts.