What Does C0306 Mean?
C0306 indicates a malfunction in the electrical circuit of Motor A or Motor B within the chassis control system. This typically relates to actuator motors used in active suspension, stability control, or active steering systems. The control module has detected an abnormal voltage, current draw, or resistance in the motor circuit indicating a short, open, or mechanical failure.
Common Causes
40%
Failed or seized actuator motor (Motor A or B)
30%
Damaged wiring harness, corroded connectors, or chafed wires in motor circuit
20%
Internal short or open circuit within the motor assembly
10%
Faulty chassis control module or motor driver circuit failure
Diagnostic Steps
1
Step 1: Perform visual inspection of all motor wiring harnesses and connectors for physical damage, corrosion, bent pins, or water intrusion. Check connector security and repair any obvious damage.
2
Step 2: Using a digital multimeter, measure resistance across motor terminals (motor disconnected) and compare to factory specifications (typically 2-15 ohms). Infinite resistance indicates open circuit; zero resistance indicates short circuit.
3
Step 3: Check motor power and ground circuits with multimeter while commanding motor actuation through scan tool bi-directional controls. Verify battery voltage on power side and good ground (<0.5 ohms) on ground side during operation.
4
Step 4: Perform current draw test on motor during actuation. Compare amperage to specifications (typically 2-8 amps). Excessive current indicates mechanical binding or internal motor fault; no current indicates open circuit or control module failure.
5
Step 5: If motor circuits test normal, suspect control module failure. Swap suspect motor with known good motor (if applicable) to isolate component vs. module failure.
6
Step 6: After repairs, clear codes, perform system initialization/calibration procedures as required, and road test vehicle while monitoring live data to confirm proper motor operation and no code recurrence.
Estimated Repair Cost
$200 - $1,200
Parts + labor, varies by vehicle and location
C0306 indicates a malfunction in the electrical circuit of Motor A or Motor B within the chassis control system. This typically relates to actuator motors used in active suspension, stability control, or active steering systems. The control module has detected an abnormal voltage, current draw, or r...
The most common cause of C0306 (Motor A or B Circuit) is: Failed or seized actuator motor (Motor A or B)
Typical repair costs for C0306 range from $200 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is generally safe to drive but may experience degraded handling characteristics, harsh ride quality, or disabled stability control features. Repair within 1-2 weeks to restore full chassis control functionality and safety systems.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C0306 to identify the root cause.
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Quick Info
Category
Chassis
System
Active Chassis Control System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
