Lexus RC Overheating Communication Error

I've got a 2017 Lexus RC hybrid with about 223k km. Recently, the check engine light popped up, and the engine's been overheating. I even noticed coolant spilling under the car, which I'm guessing is from over-pressurization in the cooling system. I scanned the car and it's showing a control unit communication error, which sounds like a connectivity issue to me. I checked some obvious things, but does anyone have experience with this? Could a faulty cable or plug connection really cause all these symptoms?

4 comment(s)

Sounds like a communication fault alright. Overheating and coolant spills are nasty. What diagnostic trouble code (DTC) are you getting? A specific code would really narrow down which control module is having issues. Also, have you checked the coolant level sensor? A faulty sensor might be sending wrong signals.

Thanks for the quick reply! The DTC is pointing towards a general communication error within the hybrid control system - nothing super specific, unfortunately. I haven't checked the coolant level sensor directly, but wouldn't that usually trigger a separate error code? Could a bad communication link really cause the system to over-pressurize like that?

Yeah, a generic communication error is annoying. A bad connection can definitely cause weird issues, including over-pressurization if it's affecting how the cooling system is being managed by the ECU (engine control unit). Given the coolant spill and overheating, and your mileage, I’d recommend getting it checked by a workshop. They'll have better diagnostic tools to pinpoint the exact location of the connectivity issue.

Thanks for the advice! Turns out it was indeed a corroded connector on one of the control modules. A quick clean and some contact spray did the trick, and the system is back to normal now. Cost me about 95€ at the shop. Appreciate the help!

Join the discussion now: