ABS Outlet Valve Circuit Open
The C1203 code indicates that the ABS control module has detected an open circuit in the rear outlet valve solenoid coil. This solenoid controls hydraulic pressure release in the rear wheels during ABS activation. An open circuit prevents the module from modulating pressure, disabling the ABS system and illuminating the ABS, VSC, and TRAC warning lights.
1. Commonly Affected Makes
2. Most Common Causes
- Damaged rear outlet valve solenoid coil in the ABS actuator (infinite resistance)
- Open, cut, or corroded wiring or connector in the rear valve circuit
- Internal failure of the ABS hydraulic unit (actuator)
- Faulty output driver in the ABS ECU
3. Symptoms You Will Notice
- ABS warning light on
- VSC and TRAC warning lights on
- ABS system disabled (wheels may lock under hard braking)
4. Step-by-Step Diagnosis
Scan for codes and verify C1203 is present
Inspect the ABS actuator wiring and connector for damage, corrosion, or loose pins
Measure resistance of the rear outlet valve solenoid at the actuator connector (spec: typically 5-20 ohms; open indicates faulty solenoid)
Check for continuity and shorts in the wiring between the ABS module and actuator
If wiring and solenoid are good, suspect a faulty ABS module or internal actuator failure
5. Frequently Asked Questions
Is it safe to drive?▼
Driving is possible but not recommended because the ABS system is disabled, increasing the risk of wheel lockup and loss of control during emergency braking. Have the vehicle repaired as soon as possible.
How much does it cost to fix?▼
Repair costs typically range from $200 to $1,200 depending on the root cause. A simple wiring repair may cost $200-$400, while replacing the ABS actuator or module can run $800-$1,200 including labor.