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Malfunction of the Hydraulic System code

This morning, during a routine drive to work in my 2007 Toyota Prius, my instrument panel lit up with the brake light and ABS light. The car braked normally, although when I tested the anti-lock brakes in a parking lot, the car slid and the ABS did not engage. I brought it to a shop - they ran a diagnostic and came up with a Malfunction of the Hydraulic System - right rear. They said I need to take it to a dealer for repairs. Does anyone know what the possible cause/fix for this is, and how much it may cost? This car has cost me a lot in repairs over the last year…and with 170,000 miles, I’m not willing to put in a lot more. Thanks!

You need to have someone inspect the right rear brake wheel cylinder for a fluid leak.

The ABS does a self test when the vehicle is first started and when the vehicle is first driven. If the ABS detects a pressure difference in the hydraulics of the brake system the brake light will come on and the ABS light will come on.

In the mean time, as long as the ABS light is on the ABS won’t function.


The dealer will be able to do further diagnosis, after which you can decide what to do. But if you’re lucky it could be as simple as replacing a bad hydraulic pressure sensor, so don’t despair yet.

If you want a bit more understanding of your braking system you can read about it here:

I found out more about the problem - I’ve been told it’s the brake actuator. I’m taking it to a dealer on Monday. Looks like this is an expensive fix, and I may be forced to decide whether fixing it is worth it, or if I’m better off getting a new car.

Thanks for the comments and suggestions!