OBD2 U0552: Running Board Module B Data Fault
The U0552 code indicates that the engine or powertrain control module (ECM/PCM) has received invalid, corrupt, or out-of-range data from the Running Board Control Module B. This module controls the deployment and retraction of the motorized side step on the vehicle. Communication occurs over the CAN bus, and invalid data may stem from incorrect message frames, checksum errors, or signal values exceeding manufacturer-defined limits.
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Internal failure of the Running Board Control Module B
- Electromagnetic interference or noise on the CAN bus
- Abnormal resistance in data bus wiring (high resistance, corroded connectors)
- Short or open circuit in the CAN-H or CAN-L communication wires from the module
- Faulty ECM/PCM misinterpreting the data
- Voltage difference or poor ground at the running board module
- Corrupted module software or incompatible version after an update
3. Symptoms You Will Notice
- Running board does not deploy or retract properly
- Running board operates erratically or intermittently
- Check Engine Light or Service Running Board warning on dashboard
4. Step-by-Step Diagnosis
Scan for all stored codes and freeze frame data
Inspect running board module connectors and wiring for corrosion, damage, or loose connections
Check CAN bus resistance and voltage at the module connector
Test communication between ECM and running board module using a scan tool
If wiring is intact, attempt to reprogram or replace the Running Board Control Module B
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, it is generally safe to drive, but the running board may not function correctly. The vehicle's core drivetrain is not affected.
How much does it cost to fix?▼
Diagnosis typically costs $100-$150. Replacing the running board module can range from $200 to $600, including parts and labor.