What Does U0251 Mean?
The network has lost communication with running board control module B, which manages the extension and retraction of power running boards. This affects vehicle entry/exit convenience features.
Common Causes
40%
Damaged wiring or connectors to running board module (exposed to road debris)
25%
Failed running board control module B
20%
Corrosion at module connector from moisture/salt exposure
10%
Physical damage to module from road debris or impact
5%
Network communication fault or short circuit
Diagnostic Steps
1
Step 1: Inspect running board module B location (typically driver or passenger side) for physical damage
2
Step 2: Check connector at running board module for corrosion, moisture intrusion, or damage
3
Step 3: Verify power and ground at module connector with multimeter
4
Step 4: Inspect underbody wiring harness for damage from road debris or pinch points
5
Step 5: Use scan tool to monitor network activity and attempt to communicate with module B
Estimated Repair Cost
$200 - $900
Parts + labor, varies by vehicle and location
The network has lost communication with running board control module B, which manages the extension and retraction of power running boards. This affects vehicle entry/exit convenience features.
The most common cause of U0251 (Lost Communication With Running Board Control Module "B") is: Damaged wiring or connectors to running board module (exposed to road debris)
Typical repair costs for U0251 range from $200 to $900, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Low safety risk. Running boards may remain extended or retracted, potentially creating a trip hazard or reducing ground clearance.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U0251 to identify the root cause.
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Quick Info
Category
Network
System
Vehicle Network Communication / Running Board System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
