Lost Communication with Airbag Module
The U0151 code indicates that the engine or powertrain control module (ECM/PCM) has lost communication with the Restraints Control Module (RCM), also known as the airbag or SRS module. This communication typically occurs over the Controller Area Network (CAN) bus. The loss can be intermittent or permanent, preventing the ECM from receiving status information from the restraint system or the RCM from receiving vehicle data needed for proper airbag deployment. The RCM continuously monitors impact sensors, seat belt pretensioners, occupant sensors, and other passive safety components. When communication is lost, the airbag system may become inoperative or operate in a degraded mode, with the airbag warning light illuminated on the dashboard.
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Faulty Restraints Control Module (RCM) due to internal damage or hardware failure
- Open, shorted, or incorrect resistance in the CAN bus wiring (CAN-H and CAN-L circuits)
- Corroded, loose, or disconnected RCM connector
- Faulty CAN bus termination module (120-ohm resistors)
- Power supply issue to the RCM (blown fuse, voltage drop, poor ground)
- Faulty ECM/PCM affecting bus communication
- Electromagnetic interference or harness damage from a collision or previous repair
3. Symptoms You Will Notice
- Airbag warning light illuminated on the dashboard
- Airbag system inoperative or degraded mode
- Possible no-start or other communication-related symptoms
4. Step-by-Step Diagnosis
Scan for additional codes and verify U0151 is present
Check for technical service bulletins (TSBs) related to the vehicle
Inspect the RCM connector for corrosion, damage, or loose pins
Test CAN bus wiring for continuity, shorts, and proper resistance (60 ohms between CAN-H and CAN-L with modules connected)
Verify power and ground at the RCM (check fuses, voltage, and ground integrity)
If wiring and power are good, suspect a faulty RCM or ECM/PCM; perform module communication tests
5. Frequently Asked Questions
Is it safe to drive?▼
No, it is not safe to drive. The airbag system may be inoperative, increasing the risk of injury in a collision. Have the vehicle diagnosed and repaired immediately.
How much does it cost to fix?▼
Repair costs vary widely depending on the cause. A simple fuse replacement may cost under $50, while replacing an RCM can range from $200 to $800 or more, including labor and programming.