OBD-II Diagnostic Trouble Code
U0143 — Lost Communication With Body Control Module C
U0143 means another module on the network stopped receiving messages from Body Control Module C for longer than the allowed time. Body Control Module C is an extra body controller used on some vehicles with distributed body electronics, and the functions it controls depend on the manufacturer. The code reports a communication timeout, which is most often caused by power, ground or wiring problems rather than an internal module failure.
Severity 3/5
Truck-relevant
Service this week
Severity
Service this week
Lost Communication With Body Control Module C
Code
U0143
Category
Network
Subsystem
Network
Truck-relevant
Yes
What this means for truckers
Service within a few days on a Cummins X15, Detroit DD15, PACCAR MX-13. Performance is likely degraded. Continuing to drive without service risks additional component damage.
Before you replace parts — try this first
U0143 on the Network system is most often open fuse, power feed or ground at body control module c — 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
Typically a warning lamp or cluster message along with loss of the body functions handled by BCM C, such as certain lighting, door, mirror or accessory circuits. The truck usually drives normally. Several U-codes may be stored together when a shared network segment is affected.
Common causes
- CommonOpen fuse, power feed or ground at Body Control Module C ($50–$250)
- CommonDamaged CAN wiring or corroded connector at the module ($150–$600)
- OccasionalLow system voltage from weak batteries or poor cable connections ($100–$900)
- RareInternal failure of Body Control Module C ($500–$1800)
How to fix
Verify battery condition and check the fuses, ignition feed and ground circuits for BCM C
When to use: First check whenever the module cannot be reached with a scan tool
Check CAN bus voltages and termination resistance, then inspect and clean connectors at BCM C
When to use: When the module has good power and ground but other modules still report losing it
Wiggle-test the harness while watching live network status to find an intermittent open or short
When to use: When the code comes and goes with vibration or road conditions
Replace and program BCM C
When to use: Only after power, ground and wiring are confirmed good
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 U0143?
U0143 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 U0143 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 — Open fuse, power feed or ground at Body Control Module C — 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 U0143 fail a DOT inspection?
U0143 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 U0143 and related codes?
U0143 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 U0143 is set without the companions, the issue is more isolated.
How do I prevent U0143 from coming back after a repair?
For U0143 (Lost Communication With Body Control Module C), 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.