JenniferRX

I had the Check VSC System, ABS and Brake indicators lights on the dash pop up out of nowhere. I was in a panic after getting a $3000 dealer repair estimate after C1241 and C1391 codes were thrown. Accumulator Leak Malfunction with a low battery positive voltage. I was not interested in forking over that cash and decided i would just drive the vehicle anyway. But, I wanted to make sure I didn't have any brake fluid leaking, so a basic check on the brake fluid revealed that it was full. After I checked that, all of the sensor warnings disappeared. Yay!

iMSQ

I would suggest to solve the C1241 code first. Google tells that there is a problem with battery (12V).
If C1391 is still On - only replacement. I did it last month (extended warranty doesn't work more). If your dealer asks $3000 - don't purchase this part at your dealer, and order the new Actuator online (I found at Longo Lexus for $1,2k+, and installed it at local dealer for 2 costs of diagnostic)

bluto5

So, it got fixed by looking at the brake fluid? Did you open the lid . I have the exact same codes with no other issues. What did Lexus tell you was wrong that miraculously healed itself..

iMSQ

Solve the cheapest code first (low battery). Then look for Actuator.
PS: If ABS is turned off then Energy recuperation doesn't work well.

95carfixer

I just ran across this thread while looking for info on similar issues with my 2006 RX400h. My daughter was driving and told me the ABS and VCS lights came on. Once she got home I checked for DLCs and found C1241 and C1391. I'm hoping that some of your experiences with unexpected low-cost fixes have been long-term successful. KlausM, I'm curious about the software you used. I followed your link, but I will wait to bring my windows laptop home before I download it.

I'll post updates as I work through this.

Crickets

The ABS, VSC lights + reduced power appeared on my IS and RX hybrid under 3 different conditions:

1. bad wheel speed sensor (IS)
2. bad MAF sensor (IS)
3. Bled rear brakes like a non hybrid by pressing brakes (RX)

For 1 and 2, problem fixed by replacing parts. For 3, lights eventually cleared.

No other DTCs?

95carfixer

No other DTCs. I cleared them, but haven't had a chance to drive it again to see if they reappear. I need to lift the hood before I do anything! Thanks for the reply.

Slowhand

I had the same issue. My anti-lock system would come randomly while driving. My local mechanic wanted $150 just to diagnose it. Said it could take 3-4 hours.
I just disabled the system by pulling the fuse. Drives great. I live where there's not too much weather and I am comfortable that I can safely drive without anti-lock brakes.