U0142 — Data Bus: Body Control Module (8CM) 8 – No Communication #

Note: The exact wording of this code may vary depending on the vehicle manufacturer (OEM). Below are some known label variations for this code:

• U0142: Lost Communication With Body Control Module – Ford, GM
• U0142: No Communication With Body Control Module (BCM) – Chrysler
• U0142: CAN Communication With BCM Fault – Volkswagen
• U0142: Data Bus: BCM No Response – Mercedes-Benz

Code Summary for U0142 #

The U0142 code indicates that your vehicle’s main computer, the Powertrain Control Module (PCM), has lost communication with the Body Control Module (BCM) over the data bus. The BCM is a vital component that manages various non-engine related systems like lighting, central locking, windows, and sometimes anti-theft devices. The data bus—often a CAN bus (Controller Area Network)—acts as the nervous system, allowing control units to exchange information. When the PCM cannot “hear” from the BCM, it sets the U0142 code. This is a communication fault, not a specific failure of a single component, and often points to wiring, connector, or module issues.

Frequent Symptoms for Code U0142 #

When U0142 is set, you may notice a range of odd behaviors in your vehicle. These symptoms usually relate to body functions—think of anything managed by buttons, switches, or interior electronics. Sometimes, the vehicle may not even show a warning light, while at other times, you’ll get a “Check Engine” or specific body system warning.

• Central locking or power windows not responding
• Interior or exterior lights malfunctioning
• Instrument cluster behaving abnormally (e.g., gauges not working)
• Alarm or anti-theft system triggering unexpectedly
• Remote keyless entry failures
• Battery drains faster than usual
• “No Communication” message on diagnostic scanner

Probable Causes for Code U0142 #

Most U0142 issues come down to communication interruptions. These can arise from wiring, connector problems, or the modules themselves. Here are the most common causes, ranked by likelihood:

1. Loose, corroded, or damaged wiring/connectors between the BCM and the rest of the network
2. Internal failure of the Body Control Module (BCM)
3. Faulty Powertrain Control Module (PCM) or other control unit
4. Blown fuses supplying power or ground to the BCM
5. CAN bus (data line) issues such as shorts to power, ground, or open circuits
6. Aftermarket accessories improperly installed (alarms, remote starts, stereos)

Step-by-Step Diagnostic for Code U0142 #

Diagnosing a U0142 code calls for a methodical approach. The key is to check communication on the data bus, inspect wiring, and verify module operation, preferably using a scan tool that can read all modules. Here’s a step-by-step plan:

• 1. Check for other codes: Scan for stored or pending codes in all vehicle modules. Related codes may pinpoint the fault.
• 2. Inspect fuses and relays: Confirm all fuses and relays for the BCM and PCM are intact and properly seated.
• 3. Visual inspection: Look for obvious wiring damage, corrosion, or loose connections at the BCM, PCM, and under the dash.
• 4. Test network communication: Use a scan tool to see if the BCM responds to commands. If “No Communication” persists, BCM power and ground must be checked.
• 5. Check CAN bus integrity: Probe CAN H and CAN L wires for continuity, shorts, or opens with a multimeter or oscilloscope if available.
• 6. Isolate module failure: If wiring is good and power/ground are present, the BCM may be faulty. Substitute with a known-good module if possible (following OEM security procedures).
• 7. Review recent work: If the fault appeared after an accessory install or repair, double-check for disturbed wiring or connectors.

Possible Repairs for Code U0142 #

Repairs should always follow the diagnosis. Since U0142 is a communication issue, the fix may be simple or require module replacement. Here’s what you might need to do, based on the underlying cause:

• Repair or replace damaged/corroded wiring or connectors between the BCM and CAN bus
• Replace blown fuses or faulty relays supplying the BCM
• Secure loose connectors at the BCM or PCM
• Remove or properly re-install aftermarket electronics interfering with the data bus
• Replace a failed Body Control Module (BCM)—may require programming/calibration by the dealer or qualified technician
• Replace the PCM if verified faulty (rare for this code)

Is It Safe to Drive With Code U0142? #

Limited. While U0142 usually doesn’t cause immediate drivability issues, it can affect important body functions like lighting, security, and window controls. In some cases, the vehicle may not start if the BCM is responsible for anti-theft functions. If you notice erratic behavior of critical systems (headlights, ignition), don’t drive the vehicle until repaired. Otherwise, avoid long trips and have the issue addressed promptly.

Vehicles Most Commonly Affected by U0142 #

U0142 is a generic communication code, but it is particularly common on models where the BCM plays a central role in body electronics. Vehicles with extensive electronic integration are more prone.

• Ford (Fusion, F-150, Escape, Focus, Explorer)
• Chevrolet (Silverado, Malibu, Equinox, Cruze)
• Chrysler/Dodge/Jeep (Ram, Grand Caravan, 300, Wrangler)
• Volkswagen (Golf, Passat, Jetta)
• Mercedes-Benz (C-Class, E-Class)
• Hyundai/Kia (Sonata, Santa Fe, Sportage)

Common Mistakes & Best Practices for U0142 #

Misdiagnosing U0142 is easy if you skip the basics. Many techs jump straight to module replacement when the real issue is a simple wiring or connector fault. Here’s what to avoid—and what to do:

• Don’t replace the BCM without confirming power, ground, and communication lines are intact
• Always check for other network-related codes in all modules
• Inspect for corrosion or water ingress, especially under carpets and kick panels
• Be wary of aftermarket alarm and remote start installations—disconnect them to test
• Use OEM wiring diagrams to trace circuits accurately
• After repairs, clear codes and verify with a test drive

Quick FAQ for Code U0142 #

Q: Can I reset the U0142 code myself?
A: You can clear the code with a scan tool, but unless the root cause is fixed, it will return. Always fix the underlying issue before clearing codes.

Q: Will replacing the battery cause a U0142 code?
A: Sometimes, battery disconnection or voltage drops can trigger temporary communication codes. If the code persists after a battery replacement and a drive cycle, further diagnosis is needed.

Q: Do I need dealer programming after replacing the BCM?
A: In most cases, yes—especially for modern vehicles with security features. The new module must be programmed/configured to your vehicle by a dealer or skilled technician with OEM-level tools.