What Does C1921 Mean?
The steering module has detected a general circuit failure in the Variable Assist Power Steering (VAPS) solenoid actuator output circuit. The module cannot properly drive the VAPS solenoid, which modulates hydraulic steering assist based on vehicle speed. Steering effort will not adjust with speed, remaining fixed at either heavy or light assist.
Common Causes
35%
Failed VAPS solenoid actuator with degraded coil or stuck valve spool
30%
Damaged wiring in the VAPS output circuit between the steering module and the solenoid
25%
Corroded connector at the VAPS solenoid from power steering fluid leakage or road spray
10%
Steering module internal output driver circuit failure
Diagnostic Steps
1
Step 1: Measure VAPS solenoid coil resistance at the solenoid connector (typical: 4-8 ohms). Infinite or very low resistance indicates solenoid failure.
2
Step 2: Verify the module is producing a PWM output signal on the solenoid drive wire using an oscilloscope.
3
Step 3: Check for power steering fluid leaks at the solenoid seal that could contaminate the electrical connector.
4
Step 4: Inspect wiring and connectors for damage, corrosion, and proper terminal tension.
5
Step 5: If the solenoid and wiring are good, monitor module commanded vs. actual current to determine if the module driver is at fault.
Estimated Repair Cost
$150 - $650
Parts + labor, varies by vehicle and location
The steering module has detected a general circuit failure in the Variable Assist Power Steering (VAPS) solenoid actuator output circuit. The module cannot properly drive the VAPS solenoid, which modulates hydraulic steering assist based on vehicle speed. Steering effort will not adjust with speed, ...
The most common cause of C1921 (VAPS Solenoid Actuator Output Circuit Failure) is: Failed VAPS solenoid actuator with degraded coil or stuck valve spool
Typical repair costs for C1921 range from $150 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Loss of variable steering assist means steering effort does not adjust with vehicle speed. This can result in dangerously light steering at highway speeds or excessively heavy steering at low speeds.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C1921 to identify the root cause.
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Quick Info
Category
Chassis
System
Variable Assist Power Steering (VAPS)
Difficulty
Type
Manufacturer
Recommended Tools
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