Avalon Hybrid Overheating Coolant Spill

I own an Avalon too, and your issues sound eerily familiar to something I went through. The overheating, check engine light, and coolant issues all point to a similar problem. Did you happen to get any diagnostic trouble codes (DTCs) read? It could be something as simple as a loose connection or a software glitch causing a communication fault within the CAN bus system. Have you tried checking the main fuses and relays related to the engine control unit (ECU)? Let me know if you have any codes!

Thank you so much for your swift response. I haven't had the chance to get any diagnostic trouble codes read yet, but it is definitely on my to-do list. As for checking the fuses and relays related to the ECU, I'm not entirely sure where to locate them in my Avalon Hybrid. Could you perhaps provide some guidance on that front? And just to confirm, were your symptoms identical to mine, including the coolant spill due to excessive pressure?

The exact location of the fuses and relays can vary slightly, but your owner's manual should have a diagram. Usually, there's a main fuse box under the hood and another one inside the cabin, often near the driver's side footwell. Look for anything labeled 'ECU,' 'Engine Control,' or something similar. And yes, my symptoms were pretty much identical, right down to the coolant spill. It turned out to be a faulty connection in the end, but it took a proper car diagnostics session to pinpoint the exact location. Honestly, I'd suggest taking it to a reputable mechanic who specializes in hybrid vehicles. They'll have the right tools and expertise to diagnose the issue accurately. Better safe than sorry, especially with potential overheating problems.

I sincerely appreciate your detailed advice and for sharing your experience. It seems prudent to heed your warning and seek professional assistance. I took it to the workshop and it was indeed a defective cable. The mechanic performed the car diagnostics and quoted me 95€ for the repair. Thank you again for your time and invaluable insights!