What Does C0499 Mean?
This code indicates the steering assist control module detected a higher than expected voltage on the power feed circuit to the steering assist control solenoid. The electronic power steering (EPS) or hydraulic power steering control module monitors the solenoid feed voltage and sets this code when it detects voltage above the normal operating range, typically above 16 volts or a short to battery voltage condition. This fault prevents proper operation of the variable steering assist system.
Common Causes
35%
Short to voltage in the solenoid feed wiring harness between the control module and solenoid valve
30%
Failed steering assist control solenoid with internal short to power
20%
Corroded or damaged connector pins causing intermittent short to voltage
15%
Failed steering assist control module with faulty driver circuit
Diagnostic Steps
1
Step 1: Perform visual inspection of the steering assist solenoid connector and wiring harness for damaged insulation, chafing against chassis/engine components, or signs of water intrusion. Inspect connector terminals for corrosion, pushed-back pins, or heat damage.
2
Step 2: With ignition off, disconnect the steering assist solenoid connector. Using a digital multimeter, check for continuity between the solenoid feed circuit terminal (at the harness side) and battery positive. Reading should be infinite resistance (open circuit). If continuity exists, there is a short to voltage in the harness.
3
Step 3: Measure resistance across the solenoid terminals with solenoid disconnected. Typical solenoid resistance should be 2-10 ohms (verify manufacturer specifications). If resistance is near zero ohms or shows short to ground, replace the solenoid.
4
Step 4: With solenoid disconnected and ignition on, use multimeter to measure voltage at the solenoid feed circuit at the harness connector. Voltage should cycle between 0V and battery voltage as the control module commands the solenoid. Constant battery voltage indicates a wiring short or failed control module.
5
Step 5: If all wiring and solenoid test normally, monitor the solenoid feed circuit voltage with an oscilloscope while operating steering through full range of motion to identify intermittent shorts caused by wire flexing or movement.
6
Step 6: Clear codes, reconnect all components, and road test vehicle while monitoring live data for solenoid voltage and current draw. Verify proper operation and that code does not return.
Estimated Repair Cost
$150 - $950
Parts + labor, varies by vehicle and location
This code indicates the steering assist control module detected a higher than expected voltage on the power feed circuit to the steering assist control solenoid. The electronic power steering (EPS) or hydraulic power steering control module monitors the solenoid feed voltage and sets this code when ...
The most common cause of C0499 (Steering Assist Control Solenoid Feed Circuit High) is: Short to voltage in the solenoid feed wiring harness between the control module and solenoid valve
Typical repair costs for C0499 range from $150 to $950, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is generally safe to drive but steering assist may be reduced or disabled, resulting in heavier steering effort especially at low speeds or while parking. Repair within a few days to restore normal steering function and prevent potential control module damage from continued electrical faults.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C0499 to identify the root cause.
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Quick Info
Category
Chassis
System
Electronic Power Steering (EPS) / Variable Assist Steering System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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