U0DA6

Lost Communication With Propulsion Power Module

U0DA6 is a generic OBD-II network diagnostic trouble code: Lost Communication With Propulsion Power Module. 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
U0DA6
Group
Network
System
Network
Severity
Critical (limp mode / no-start)
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What U0DA6 means

U0DA6 is stored when the vehicle network loses communication with the propulsion power module, which is the central ECU responsible for managing propulsion power delivery in electric or hybrid drive systems. This module coordinates power flow between the high-voltage battery, motor inverter(s), and drivetrain, and is a critical node in the traction control network. Loss of communication with this module directly threatens the vehicle's ability to generate drive force.

Because the propulsion power module governs the primary drive system, its absence from the CAN network typically triggers an immediate safe-mode response: the vehicle may reduce power to a minimal level, enter a fail-safe drive mode, or prevent propulsion entirely. This code is treated as a critical fault because it represents a potential total loss of drive and a high-voltage system safety concern.

Diagnosis must be conducted under strict high-voltage safety protocols. The first step is always to confirm the module's 12V control supply and ground, since a missing supply voltage will make the module appear completely absent from the network. Co-set codes from the inverter, motor control, and battery management modules will help build a full picture of the network state before any high-voltage components are approached.

Common causes

Most-frequently reported root causes when U0DA6 is logged.

  • 1
    Loss of 12V control supply voltage or ground to the propulsion power module.
  • 2
    Open or shorted CAN bus wiring on the high-voltage system network segment.
  • 3
    Failed propulsion power module no longer transmitting on the vehicle CAN network.
  • 4
    Corroded or damaged connector at the propulsion power module.
  • 5
    High-voltage interlock loop (HVIL) fault causing the module to shut down.
  • 6
    Thermal protection event causing the module to disable its own communication.
  • 7
    Recent service disturbing the module wiring, grounding, or CAN bus connections.

Symptoms drivers notice

Reduced power or no propulsion available; vehicle may not move.
High-voltage system warning or power train error displayed in the instrument cluster.
Scan tool cannot establish communication with the propulsion power module.
Multiple related high-voltage system communication faults may be present.
Vehicle may enter a restricted limp-home mode or refuse to start.

How to diagnose U0DA6

A typical diagnostic flow when this code is present.

  1. 1
    Apply all high-voltage safety precautions before beginning; disable the high-voltage system per manufacturer procedure.
  2. 2
    Retrieve all DTCs from all available modules and document co-set codes from inverter, battery, and motor control modules.
  3. 3
    Verify 12V control supply voltage and ground at the propulsion power module connector.
  4. 4
    Inspect the module connector and harness for damage, corrosion, or dislodged terminals.
  5. 5
    Check the high-voltage interlock loop (HVIL) integrity if applicable to the platform.
  6. 6
    Measure CAN bus differential voltage at the module connector to confirm network signal presence.
  7. 7
    If supply, ground, and CAN bus are confirmed and no communication is established, the module has likely failed; follow manufacturer high-voltage replacement procedures.

Related network codes

Frequently asked questions

Can U0DA6 occur without any high-voltage fault?

Yes. The communication loss itself is a low-voltage network fault and can occur even if the high-voltage system is otherwise healthy. A failed 12V supply to the module is a common cause unrelated to high-voltage system health.

Is U0DA6 always a no-start condition?

Not always, but it frequently results in a severe power reduction or loss of propulsion because the propulsion power module coordinates drive system output. The exact behavior depends on the platform fail-safe strategy.

Do I need a dealer scan tool to diagnose U0DA6?

Full diagnosis typically requires a manufacturer-specific or enhanced scan tool that can interrogate all ECUs on the high-voltage system network, as generic OBD-II tools may have limited access to propulsion system modules.

Could a 12V battery failure trigger U0DA6?

Yes. A discharged or failed 12V auxiliary battery can prevent the propulsion power module from booting and communicating, making U0DA6 one of the first codes set when the 12V system collapses on a hybrid or electric vehicle.

Disabling U0DA6 in software

RaceTune can permanently disable U0DA6 — 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.

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