U061F

Lost Communication With Body Control Module 'B'

U061F is a generic OBD-II network diagnostic trouble code: Lost Communication With Body Control Module 'B'. It is logged by the engine control unit when the network monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
U061F
Group
Network
System
Network
Severity
Warning (MIL on)
Need U061F disabled?
RaceTune permanently disables any OBD-II trouble code on supported ECUs — for motorsport, off-road, and export use.
→

What U061F means

U061F is set when a control module on the vehicle communication network is unable to receive expected messages from Body Control Module B (BCM-B) within a calibrated time window. Body Control Module B typically governs a secondary cluster of body electronics such as rear lighting, climate zone control, or auxiliary power distribution on larger vehicles with split BCM architecture.

The fault is almost always a network-layer issue: the receiving module sees no traffic on the bus from BCM-B for a defined number of message cycles. Root causes include an open or shorted CAN bus wire, a failed BCM-B processor, a blown supply fuse, or a poor ground connection at the module. Intermittent contact in a wiring harness connector is a common trigger on higher-mileage vehicles.

Because BCM-B controls body functions rather than engine management, the MIL is illuminated as a network integrity warning but the engine generally continues to run. Ancillary features such as rear HVAC, certain lighting circuits, or entertainment bus nodes may become non-functional until communication is restored.

Common causes

Most-frequently reported root causes when U061F is logged.

  • 1
    Open circuit or short to ground on the CAN bus wiring between BCM-B and the gateway module.
  • 2
    BCM-B power supply fuse blown or relay failed.
  • 3
    Poor or corroded ground connection at the BCM-B mounting point.
  • 4
    BCM-B internal processor failure or corrupted firmware.
  • 5
    Damaged or water-intruded wiring harness connector at BCM-B.
  • 6
    Excessive bus load caused by another module holding the CAN bus dominant.
  • 7
    Failed CAN bus termination resistor causing network signal reflections.

Symptoms drivers notice

MIL or network warning lamp illuminated.
Rear HVAC, lighting, or other BCM-B-governed functions inoperative.
Multiple additional U-codes stored in other modules that also lost BCM-B messages.
Scan tool unable to communicate with BCM-B.
Intermittent electrical accessories cutting out.

How to diagnose U061F

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool and record all stored DTCs across all modules before clearing anything.
  2. 2
    Attempt to establish serial communication with BCM-B and note whether the module responds at all.
  3. 3
    Verify BCM-B power supply fuses and relay outputs with a voltmeter.
  4. 4
    Inspect BCM-B ground straps for corrosion or looseness and measure ground resistance.
  5. 5
    Visually inspect the CAN bus wiring and connectors serving BCM-B for damage, corrosion, or water intrusion.
  6. 6
    Measure CAN Hi and CAN Lo voltages at the BCM-B connector with the network active and compare against nominal values.
  7. 7
    If wiring and power are confirmed good, perform a BCM-B module reset or reflash before condemning the module.

Related network codes

Frequently asked questions

Can I drive with U061F set?

Short-term driving is usually possible because the engine is unaffected, but body functions controlled by BCM-B may be non-operational, which could include lighting or climate, so prompt diagnosis is advised.

Will U061F clear itself after a repair?

Most control modules self-clear a lost-communication code after a set number of successful message cycles once communication is restored; otherwise clear it with a scan tool after confirming the fix.

Can a dead battery cause U061F?

Yes. A low or failing battery can cause modules to drop off the bus, generating lost-communication codes that disappear after the battery is charged or replaced.

Is BCM-B the same as the main BCM?

No. Vehicles with a split body-control architecture have a primary BCM-A and a secondary BCM-B handling different zones or subsystems; U061F specifically targets the secondary unit.

Disabling U061F in software

RaceTune can permanently disable U061F — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

Got U061F in your scan?

Upload your ECU file — we'll identify the exact software version and confirm whether a disable is available for your car.

Upload your file