OBD-II Diagnostic Trouble Code
U0142 — Lost Communication With Body Control Module B
U0142 sets when a module on the vehicle network stops receiving expected messages from Body Control Module B within the allowed time window. On vehicles that split body functions across several controllers, BCM B usually handles a secondary group of body loads, and which functions it covers varies by manufacturer. The fault means the receiving module saw the message timeout, not necessarily that BCM B itself failed.
Severity 3/5
Truck-relevant
Service this week
Severity
Service this week
Lost Communication With Body Control Module B
Code
U0142
Category
Network
Subsystem
Network
Truck-relevant
Yes
What this means for truckers
U0142 (Lost Communication With BCM B) — secondary BCM offline.
Before you replace parts — try this first
U0142 on the Network system is most often blown fuse, loose power feed or poor ground at bcm b — not a dead part. On commercial diesels especially, work these in order before spending money on parts:
- Confirm the symptoms. Match what your truck is doing to the Symptoms section below. If the code is set but the symptoms are not there, clear the code and re-test after a drive cycle — it may not return.
- Clean and dry the sensor connector. Water, road salt, or oil seeping into a connector is the #1 fake sensor failure. Disconnect, look for green corrosion or moisture, spray with electrical contact cleaner, dry, reseat. Many faults clear here for $0.
- Inspect the wiring harness. Trace the wire from the sensor toward the ECM — look for chafing against the engine block, melted insulation near the turbo or exhaust, or pinch points where a clamp has rubbed through.
- Test the sensor before swapping it. Most Common Causes (below) list the expected voltage or resistance range — a $20 multimeter saves a $300 sensor swap that does not fix the problem.
- Only then, replace the part. Use the OEM or a tier-1 aftermarket. Cheap sensors throw the same code in two weeks.
Symptoms
Usually a warning light or message on the cluster with one group of body functions not working, such as some exterior lamps, door locks, wipers or cab accessories. Engine performance is normally unaffected, but other U-codes often set at the same time if the cause is a shared power, ground or network wiring problem.
Common causes
- CommonBlown fuse, loose power feed or poor ground at BCM B ($50–$250)
- CommonCorroded or loose connector or chafed CAN wiring between BCM B and the network ($150–$600)
- OccasionalLow battery voltage or failing charging system causing module resets ($150–$900)
- RareFailed Body Control Module B ($500–$1800)
How to fix
Check battery voltage and all fuses, power feeds and grounds to BCM B with a meter under load
When to use: First step, especially when the module is completely silent on the scan tool
On a two-wire high-speed CAN bus, measure CAN high and low voltages and, with the key off, about 60 ohms termination resistance at the diagnostic connector, then inspect BCM B connectors for corrosion or pushed-back pins
When to use: When power and ground are good but the module still drops off the network; some body networks are low-speed or single-wire and are checked per the OEM procedure instead
Repair chafed harness sections, especially where wiring passes through the cab or near the frame and clips
When to use: When the code is intermittent and changes with bumps, vibration or flexing the harness
Replace and program BCM B with the correct software
When to use: Only after confirming good power, ground and network wiring and the module still will not communicate
Affects most
No specific vehicle pattern found in our complaint database. This code can appear on any vehicle that supports OBD-II diagnostics.
Related
- → Browse all DTC trouble codes
- → Decode a VIN to check codes for your truck
- → Owner-operator maintenance guides
- → U0100 — Lost Communication With ECM/PCM A
- → U0101 — Lost Communication With TCM
- → U0102 — Lost Communication With Transfer Case Control Module
- → U0103 — Lost Communication With Gear Shift Module
- → U0104 — Lost Communication With Cruise Control Module
Frequently Asked Questions
Can I drive with code U0142?
U0142 is severity 3 — plan service within a few days. Performance is likely degraded already (you may feel reduced power, harsher shifts, or slightly worse fuel economy). Continuing to drive risks additional damage to adjacent components.
How much does it cost to fix U0142 on a commercial truck?
Total repair cost ranges $50–$1800 depending on the root cause. The cheapest fix is usually the first one listed below — Blown fuse, loose power feed or poor ground at BCM B — which is also the most common. On commercial trucks the cost is usually higher than passenger vehicles due to part availability and shop labor rates ($120–185/hour at most truck shops, vs $90–130 at general auto shops). DIY-capable fixes (sensors, hoses, filters) are at the low end; major component replacements (turbo actuator, high-pressure fuel pump, transmission solenoid pack) are at the high end. Always diagnose with a scan tool BEFORE replacing parts — guessing wrong on a $1,500 turbo actuator when the actual issue was a $30 boost hose is a common expensive mistake.
Will U0142 fail a DOT inspection?
U0142 is generally not a direct DOT inspection fail item by itself. Inspectors focus on safety-critical systems (brakes, steering, tires, lights, hours-of-service). However, the check engine light alone can trigger additional inspection scrutiny. Best practice: fix the code and clear it before a planned inspection.
What's the difference between U0142 and related codes?
U0142 is closely related to: U0100 (Lost Communication With ECM/PCM A), U0101 (Lost Communication With TCM), U0102 (Lost Communication With Transfer Case Control Module), U0103 (Lost Communication With Gear Shift Module). These codes share the same subsystem (network) and often appear together. If you see this code, scan for the full code list — fixing the root cause usually clears multiple companion codes at once. If only U0142 is set without the companions, the issue is more isolated.
How do I prevent U0142 from coming back after a repair?
For U0142 (Lost Communication With Body Control Module B), prevention centers on the network system. Pay attention to ground connections at every PM — bad grounds are 70% of communication codes. Inspect harness routing for chafe points. Don't disconnect modules with the key on.