C0059high severityChassis
ABS Isolation Valve Solenoid Circuit
on 2004 Subaru Legacy 3.0L H6 · AWD
What this code means
Malfunction in the ABS isolation valve solenoid, used to isolate the master cylinder from the ABS modulator.
Symptoms
- ABS light on
- Brake pedal feels unusual
- ABS not functioning
- Pedal sinks during ABS activation
Common causes
- Isolation valve solenoid failure
- ABS module internal fault
- Wiring open or short
- Contaminated brake fluid
Diagnostic steps
- Test solenoid resistance through connector
- Command isolation valve with scan tool
- Check brake fluid condition
- Inspect module connector pins
Repair notes
Replace ABS modulator assembly. Bleed brake system thoroughly.
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