Steering Assist Control Solenoid Return Circuit High (GM)
The C0504 code means the vehicle's onboard diagnostic system has detected: Steering Assist Control Solenoid Return Circuit High (GM). This is a serious severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $150 - $900 (sensor or wiring; steering assist components at the high end)
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What Are the Symptoms of C0504?
- Steering effort wrong - too heavy or overly light
- Warning light or message on
- Assist may vary with speed incorrectly
What Causes C0504? (Most Likely First)
- Fault in the power steering assist component this code names (Steering Assist Control Solenoid Return Circuit High) High
- Damaged wiring or a corroded connector in that circuit - road-splash zones corrode connectors High
- Failed related sensor or actuator Moderate
- Control module fault Low
Can I Still Drive with C0504?
Yes, but fix soon. C0504 is rated serious severity. It is not an immediate stop-driving fault, but it will not clear itself — book the repair rather than ignoring the light.
Frequently Asked Questions
What does C0504 mean?
C0504 is a chassis code used primarily by GM vehicles: Steering Assist Control Solenoid Return Circuit High. It concerns the power steering assist system.
Can I keep driving with C0504?
Generally yes; the power steering assist system may be degraded. Diagnose soon, and treat any brake- or steering-related behavior change as urgent.
Is C0504 the same on every make?
The decimal C0xxx range is dominated by GM's assignments (Chevrolet, GMC, Buick, Cadillac). Other makes may use this ID differently - if your vehicle is not a GM product, verify the meaning in your make's service information.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose C0504?
-
Read the code with a GM-capable scan tool and note the symptom byte/subcode if shown.
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View live data for the named circuit (e.g. all four wheel speeds while rolling for wheel-speed codes).
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Inspect the circuit's wiring and connectors - chassis harnesses live in the splash zone and corrode first.
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Follow the GM pinpoint test for C0504 before replacing components.
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
Which Vehicles Commonly Get C0504?
- Chevrolet, GMC, Buick, Cadillac (GM chassis code range)
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