The U0167 diagnostic trouble code (DTC) signals a critical problem in a vehicle's communication network. It indicates that the vehicle's primary computer, typically the Engine Control Module (ECM) or Powertrain Control Module (PCM), has lost communication with the Vehicle Immobilizer Control Module. This lost communication can prevent the vehicle from starting and requires immediate attention to diagnose and rectify the underlying issue.
This communication breakdown prevents the ECM/PCM from receiving the necessary authorization signal from the immobilizer, effectively shutting down the engine and preventing theft. Addressing the U0167 code promptly is essential to restore vehicle functionality and security.
| Topic | Description | Potential Causes |
|---|---|---|
| Definition | "Lost Communication With Vehicle Immobilizer Control Module." Indicates the ECM/PCM cannot communicate with the immobilizer module. | N/A |
| Symptoms | Vehicle will not start, security light illuminated, possible other communication-related DTCs. | N/A |
| Immobilizer Module Function | Prevents unauthorized vehicle operation by requiring a valid key or transponder signal. Communicates with the ECM/PCM to authorize engine start. | N/A |
| Common Causes | Faulty immobilizer module, wiring harness issues, connector problems, CAN bus issues, ECM/PCM malfunction, low battery voltage, software glitches. | N/A |
| Diagnostic Steps | Check for other DTCs, visually inspect wiring and connectors, test immobilizer module power and ground, check CAN bus integrity, scan immobilizer module for internal faults, reprogram/replace immobilizer module or ECM/PCM. | N/A |
| CAN Bus | Controller Area Network; a communication network that allows various vehicle modules to communicate. The immobilizer module and ECM/PCM rely on the CAN bus to exchange data. | N/A |
| Wiring Issues | Damaged, corroded, or shorted wiring can interrupt communication between the immobilizer module and the ECM/PCM. This includes power, ground, and CAN bus wires. | Broken wires, frayed insulation, corroded terminals, loose connections. |
| Connector Problems | Corroded or loose connectors can also disrupt communication. Check the connectors at the immobilizer module, ECM/PCM, and any intermediate junction points. | Corrosion, bent pins, loose or damaged connector housings. |
| ECM/PCM Malfunction | Although less common, a faulty ECM/PCM can be the cause. This is usually determined after ruling out other possibilities. | Internal ECM/PCM failure, corrupted software. |
| Immobilizer Module Failure | The immobilizer module itself may be faulty. This can be due to internal component failure or corrupted software. | Internal component failure, corrupted software, physical damage. |
| Low Battery Voltage | Low battery voltage can cause communication issues between modules. Ensure the battery is properly charged and in good condition. | Weak battery, corroded battery terminals, faulty alternator. |
| Software Glitches | Software glitches in either the immobilizer module or the ECM/PCM can sometimes cause communication problems. Reprogramming the affected module may resolve the issue. | Corrupted software, incomplete software updates. |
| Security System Interference | Aftermarket security systems or remote start systems can sometimes interfere with the immobilizer system. | Incorrect installation, faulty aftermarket components. |
| Tools Required | OBD-II scanner, multimeter, wiring diagrams, CAN bus analyzer (optional). | N/A |
| Related DTCs | U0001, U0100, U0101, U0140, U0155, and other U-codes related to lost communication with other modules. | N/A |
| Severity | High. The vehicle will likely not start, rendering it unusable. | N/A |
| Repair Costs | Varies greatly depending on the cause. Could range from a simple wiring repair to replacing the immobilizer module or ECM/PCM. Diagnosis can also be a significant cost. | N/A |
| Testing CAN Bus | Using an oscilloscope or CAN bus analyzer to verify proper CAN bus signal activity. Looking for correct voltage levels and signal patterns. | Shorted CAN bus wires, open CAN bus wires, faulty terminating resistors. |
| Reprogramming | Reflashing the ECM/PCM or immobilizer module with the latest software from the manufacturer. Requires specialized equipment and software. | Corrupted software, software updates to address known communication issues. |
| Key Transponder Issues | The key transponder chip itself might be faulty or not properly programmed to the immobilizer system. | Damaged transponder chip, unprogrammed key, low transponder battery (if applicable). |
| Location of Immobilizer | The immobilizer module's location varies by vehicle make and model. It's often near the steering column, instrument panel, or under the seats. Consult your vehicle's service manual. | N/A |
Detailed Explanations
Definition: The U0167 DTC means the ECM/PCM (Engine Control Module/Powertrain Control Module) is unable to communicate with the Vehicle Immobilizer Control Module. This communication is crucial for authorizing engine start.
Symptoms: The most prominent symptom is that the vehicle will not start. The security light on the dashboard will likely be illuminated. Other communication-related DTCs might also be present.
Immobilizer Module Function: The immobilizer module is a security feature designed to prevent vehicle theft. It requires a valid key or transponder signal before allowing the engine to start. It achieves this by communicating with the ECM/PCM to verify the key's authenticity.
Common Causes: The most frequent causes include a faulty immobilizer module, wiring harness problems, connector issues, CAN bus problems, ECM/PCM malfunction, low battery voltage, and software glitches.
Diagnostic Steps: Begin by checking for other DTCs, as these can provide clues. Visually inspect the wiring and connectors associated with the immobilizer module and ECM/PCM for damage or corrosion. Test the immobilizer module's power and ground circuits. Check the CAN bus integrity. Scan the immobilizer module for internal faults using a diagnostic scanner. Finally, consider reprogramming or replacing the immobilizer module or ECM/PCM if other tests fail.
CAN Bus: The Controller Area Network (CAN) bus is a communication network that allows various electronic control units (ECUs) in the vehicle to communicate with each other. The immobilizer module and the ECM/PCM use the CAN bus to exchange data, including the key authentication signal.
Wiring Issues: Damaged, corroded, or shorted wiring can interrupt the communication between the immobilizer module and the ECM/PCM. Focus on checking the wiring related to power, ground, and the CAN bus connections. Look for broken wires, frayed insulation, and corroded terminals.
Connector Problems: Corroded or loose connectors can also disrupt communication. Carefully inspect the connectors at the immobilizer module, ECM/PCM, and any intermediate junction points. Look for corrosion, bent pins, and loose or damaged connector housings.
ECM/PCM Malfunction: While less common, a faulty ECM/PCM can be the cause of the U0167 code. This is generally considered after ruling out other potential issues. Internal ECM/PCM failures or corrupted software can prevent communication.
Immobilizer Module Failure: The immobilizer module itself may be faulty. This can be due to internal component failure (such as a failed processor or memory chip) or corrupted software. Physical damage to the module can also cause it to fail.
Low Battery Voltage: Low battery voltage can cause communication issues between various modules in the vehicle, including the immobilizer module and the ECM/PCM. Ensure the battery is properly charged and in good condition. Check for a weak battery, corroded battery terminals, and a faulty alternator.
Software Glitches: Software glitches in either the immobilizer module or the ECM/PCM can sometimes cause communication problems. Reprogramming the affected module with the latest software from the manufacturer may resolve the issue.
Security System Interference: Aftermarket security systems or remote start systems can sometimes interfere with the vehicle's immobilizer system, leading to communication problems. This is especially true if the aftermarket system was not installed correctly or if it is malfunctioning.
Tools Required: The essential tools for diagnosing a U0167 code include an OBD-II scanner, a multimeter, and wiring diagrams specific to the vehicle. A CAN bus analyzer can be helpful for more in-depth troubleshooting of the CAN bus network.
Related DTCs: Other U-codes related to lost communication with other modules, such as U0001 (High Speed CAN Communication Bus), U0100 (Lost Communication With ECM/PCM "A"), U0101 (Lost Communication With TCM), U0140 (Lost Communication With Body Control Module), and U0155 (Lost Communication With Instrument Panel Cluster Control Module), can often accompany the U0167 code and provide further diagnostic information.
Severity: The severity of the U0167 code is high. The vehicle will likely not start, rendering it unusable until the issue is resolved. This can be a significant inconvenience and may require professional repair.
Repair Costs: Repair costs can vary greatly depending on the underlying cause of the U0167 code. A simple wiring repair might be relatively inexpensive, while replacing the immobilizer module or ECM/PCM can be significantly more costly. The diagnostic process itself can also contribute to the overall cost, especially if the problem is difficult to pinpoint.
Testing CAN Bus: Testing the CAN bus involves using an oscilloscope or a specialized CAN bus analyzer to verify proper signal activity. The analyzer will look for the correct voltage levels and signal patterns to ensure that the CAN bus is functioning correctly. Common problems include shorted CAN bus wires, open CAN bus wires, and faulty terminating resistors.
Reprogramming: Reprogramming involves reflashing the ECM/PCM or immobilizer module with the latest software version from the vehicle manufacturer. This requires specialized equipment and software and should only be performed by a qualified technician. Reprogramming can address corrupted software or software updates designed to resolve known communication issues.
Key Transponder Issues: If the key transponder chip is faulty, damaged, or not properly programmed to the immobilizer system, it can trigger the U0167 code. A damaged transponder chip, an unprogrammed key, or a low transponder battery (if applicable) can all prevent the immobilizer system from recognizing the key.
Location of Immobilizer: The location of the immobilizer module varies depending on the vehicle make and model. It is often located near the steering column, under the instrument panel, or under one of the seats. Consulting the vehicle's service manual is essential for locating the immobilizer module.
Frequently Asked Questions
What does the U0167 code mean? It means the vehicle's main computer (ECM/PCM) cannot communicate with the immobilizer module.
Can I fix the U0167 code myself? Some basic checks like inspecting wiring and battery voltage can be done, but professional diagnosis is often needed.
Will my car start with a U0167 code? Probably not. The immobilizer prevents engine start when communication is lost.
Is the U0167 code a serious problem? Yes, it prevents the vehicle from starting and indicates a significant communication issue.
How much does it cost to fix a U0167 code? Costs vary greatly depending on the cause, ranging from wiring repairs to module replacement.
Conclusion
The U0167 DTC indicates a critical communication failure between the ECM/PCM and the vehicle immobilizer module. A systematic approach to diagnosis, starting with basic checks and progressing to more advanced testing, is crucial for identifying and resolving the underlying cause. Professional assistance may be required for accurate diagnosis and repair, especially when dealing with complex electrical systems and module reprogramming.