P1497

P1497 on a Toyota Prius means the Inverter Cooling System Error — the hybrid power-control unit (PCU) has its own dedicated low-temperature coolant loop separate from the engine cooling system, and P1497 sets when the inverter coolant temperature sensor, the inverter electric water pump, or the loop's flow integrity is out of spec. Healthy inverter coolant runs 60-150°F under normal operation (versus the engine loop which runs 180-210°F), and the inverter electric pump draws 0.5-1.5A continuously when the hybrid system is ready. Cheapest-first ladder: (1) check the inverter coolant reservoir level first — it's a separate plastic tank near the firewall on Gen 2 (2004-2009) and tucked behind the headlight on Gen 3 (2010-2015), and the pump cavitates and the temp sensor reads out-of-range the moment the level drops below the LOW mark. Topping off with Toyota Super Long Life Coolant (pink) closes this code roughly 30% of the time. (2) Listen for the inverter pump running with the car in READY mode — it should run continuously with an audible electric whine; if it's silent, pull the pump connector and check for 12V on the supply pin and current draw of 0.5-1.5A. A locked-rotor pump reads 0A or pins at fuse-blow current. (3) Scan inverter coolant temp on the hybrid ECU PIDs (Techstream or compatible scan tool required); healthy temp at warm idle reads 80-120°F. If the sensor reads -40°F (open circuit) or 250°F+ (shorted), the temp sensor or its harness is the fault. Expensive-misdiagnosis caveat: do not replace the inverter assembly for P1497 — the inverter itself is a $3,500-$5,500 part and the fault is virtually always in the cooling loop (pump, coolant level, sensor, or hose) which together total $50-$250.

Vehicle-specific patterns: 2004-2009 Toyota Prius Gen 2 (1NZ-FXE 1.5L) is the most common P1497 platform — the inverter electric water pump (Aisin part) has a documented failure pattern around 150K-200K mi where the impeller bearing fails, and the pump goes silent. Toyota issued enhanced warranty coverage on the pump for some VINs. 2010-2015 Prius Gen 3 (2ZR-FXE 1.8L) throws P1497 with a similar pattern but the pump tends to last longer (200K+ mi) and the temp sensor itself is a more common failure mode on Gen 3. 2012-2017 Prius v wagon and 2012-2015 Prius c also share the same architecture and the same fault modes. 2006-2008 Lexus RX400h and 2010-2015 RX450h hybrid use a similar but larger inverter cooling loop with the 2GR-FXE/3MZ-FXE V6 hybrid and throw P1497 from the same root causes. Estimated repair: $50 to $450.