2008 with 245,000 miles. Master warning and problem appear on screen with HIGH ENGINE COOLANT TEMP. had the coolant flushed and filled it was fine for a week. Then started again same wanting lights and message. Husband replaced engine water pump, no improvement. Now everyday we add coolant and bleed air with cabin heater on so we can drive to work and back. There was a leak but couldn't figure out from where. Now no leak and high engine coolant still appearing. Invested In a scan gauge and the weirdest part is that the only code the car stores is for the cat converter. P0420. Even when warning light come on, no codes appear for anything goes relating to cooling. Everytime this happens, it's after or during a 40ish min drive, freeway or not. Cabin blows no hot air. Questions: 1. Could this HIGH ENGINE COOLANT TEMP be for the inverter/electrical engine? 2. Any ideas that can help us find a resolution?? Any input is much appreciated! But don't tell me to go to toyota because I can't afford thousands of dollars for the guessing game Posted via the PriusChat mobile app.
Also, overflow tank is always more than full. Q#3 If there is airlock or a leak, why does bleeding and adding coolant fix temporarily? We tried to do a pressure test but couldn't get our hands on an adapter at auto parts stores that fit our radiator cap. Ugh. Will get back with results once it arrives from amazon. Posted via the PriusChat mobile app.
Unless you picked up a mini-VCI cable (and the proper Toyota software) you most likely won't be getting all of the codes that are potentially available.
If you only ran the cabin heater to bleed air, you probably didn't get it all. You should run the CHRS pump, and use the bleeder valve at the radiator. Plenty of videos and threads here on that. I did a pressure test on my Prius last year, and had the same experience with not being able to find an adapter at the rental places, so I bought one then sold it after the test.