Lexus GS Intermittent Power Issue

I had a similar issue with my GS. I'd check the charging system thoroughly. A bad alternator or voltage regulator can cause weird electrical issues like that. Also, give the wiring harness a good look for any signs of damage or corrosion. That can cause intermittent problems too.

Thanks for the tip! When you say charging system, do you mean specifically the alternator output? And where exactly on the wiring harness should I be focusing my attention?

Yes, alternator output specifically. The voltage should be consistent when the engine is running. As for the wiring harness, start by checking the connections at the battery and the alternator itself, then trace the main power wires looking for any signs of fraying or damage. Honestly though, I'd take it to a reliable workshop to get properly checked.

Thanks, I took your advice and brought it to a workshop. Turns out, the battery was indeed defective and causing the intermittent power issue. New battery and diagnostic came out to 290€. Appreciate the help!