Code
C2357
HYUNDAI
C — Chassis
Rear Supply/Exhaust Valve AB
Views:
UK: 13
EN: 30
RU: 14
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring to the rear supply/exhaust valve
- Corroded or loose connector at the ABS hydraulic unit
- Failed solenoid (stuck, electrically open or shorted)
- Internal hydraulic leak or valve spool seizure inside the ABS modulator
- Faulty ABS/ESC control module
- Low or contaminated brake fluid affecting valve operation
Symptoms
- ABS warning lamp and/or ESC/TC warning lamp illuminated
- ABS may not function correctly (pulsing absent or constant)
- Loss of ABS or reduced stability control functionality
- Longer braking distances or unexpected ABS activation
- Brake pedal feel changes (may be firmer or softer during ABS operation)
- Possible diagnostic trouble codes stored for other ABS components
What to check
- Read ABS/ESC codes and freeze frame data with a capable scan tool
- Record related codes (wheel sensors, pump, other valve circuits)
- Visual inspection of ABS hydraulic unit, connectors and wiring for damage or corrosion
- Check battery voltage and ground integrity before functional tests
- Check brake fluid level and condition
- Test connector pins for proper voltage and ground with ignition ON and during ABS activation
Signal parameters
- Supply voltage to valve connector: ~11–14 V with ignition ON (vehicle battery voltage)
- Ground/pulse control from ABS module: switched ground or PWM signal (duty cycle varies during modulation)
- Solenoid coil resistance: typically low ohms (examples 5–30 Ω) — consult vehicle-specific spec
- During actuation: pulsed current with varying duty cycle and frequency (varies with ABS event)
- Open-circuit or short-to-ground/short-to-V circuits will deviate from above
Diagnostic algorithm
- Connect a scan tool and confirm code C2357. Note any related codes and freeze frame data.
- Check battery voltage (>=12 V) and good chassis/engine grounds.
- Visually inspect the ABS hydraulic unit, harness and connector for damage, corrosion, moisture, or fluid leaks. Repair as needed.
- With ignition OFF, disconnect the ABS hydraulic unit connector and inspect pins. Check for bent pins, corrosion or water intrusion.
- Measure solenoid coil resistance at the valve connector. Compare to vehicle specification. Replace valve if out of range or open/shorted.
- With a lab scope or multimeter, verify supply voltage and ground at the connector with ignition ON. There should be battery voltage and a switching ground or PWM when commanded.
- Use a scan tool to command the rear supply/exhaust valve and observe live data and any change in current, resistance or hydraulic response. Listen for valve operation.
- If electrical signals are correct but valve does not operate, suspect internal hydraulic/mechanical failure — remove and bench-test or replace the ABS hydraulic unit/valve block per service manual.
- If wiring or connector faults are found, repair wiring, clean/replace connector and retest.
- After repair or replacement, clear codes, perform ABS system self-test and bleed brakes if hydraulic work was done. Road test to confirm proper ABS/ESC operation and that code does not return.
- Note: When working on brake hydraulics, follow manufacturer service procedures, use correct brake fluid, and bleed the system as required.
Likely causes
- Damaged harness or pin corrosion at the ABS hydraulic unit connector
- Solenoid coil within the valve has failed (electrical resistance out of spec)
- Hydraulic valve mechanically seized by contamination or corrosion
- Intermittent communication or control signal from ABS module
- Brake fluid level low or fluid contaminated with moisture/particles
Fault status
Status
Rear supply/exhaust valve AB — electrical or hydraulic malfunction detected
Repair difficulty: Medium
Diagnostic time: 0.5-2.5 hours
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