U019F

Lost Communication With Battery Sensor Control Module B

U019F is a generic OBD-II network diagnostic trouble code: Lost Communication With Battery Sensor 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
U019F
Group
Network
System
Network
Severity
Warning (MIL on, possible limp mode)
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What U019F means

U019F sets when a control module -- commonly the ECM or PCM -- stops receiving the expected periodic serial data messages from the Engine Coolant Pump Control Module. On vehicles fitted with an electric or electronically controlled coolant pump, this module manages pump operation to regulate engine and, on some applications, turbocharger or hybrid-component temperatures. The ECM commands a desired flow or duty over the data bus and monitors the pump module's status reports. When those reports stop arriving, U019F is stored.

Because the coolant pump is central to thermal management, a loss of communication can compromise cooling if the pump defaults to a reduced or off state. Many strategies fail the pump to a safe fixed output or command auxiliary cooling, but the vehicle should be treated as at risk of overheating until the fault is confirmed and repaired. Watch coolant temperature closely.

Diagnosis begins with reading all stored codes and freeze-frame data, then confirming battery and charging health, since low voltage is a frequent cause of communication codes. Verify power and ground at the coolant pump module, inspect the CAN wiring and connectors for damage or corrosion, and attempt direct scan-tool communication before replacing the module. A replacement module may require programming.

Common causes

Most-frequently reported root causes when U019F is logged.

  • 1
    Weak or discharged battery causing the pump module to reset or drop offline.
  • 2
    Open or short in the CAN bus wiring between the ECM and the coolant pump control module.
  • 3
    Corroded, loose, or damaged connector at the coolant pump module.
  • 4
    Blown fuse or open ground on the pump module supply circuit.
  • 5
    Internal hardware failure of the Engine Coolant Pump Control Module.
  • 6
    Moisture or heat damage to the module or harness in the engine bay.
  • 7
    Coolant pump module not programmed or configured after replacement.

Symptoms drivers notice

MIL illuminated, sometimes with a coolant temperature or cooling-system warning.
Engine coolant temperature higher than normal or slow to stabilise.
Cooling fan may run continuously as a compensating strategy.
Reduced power or limp mode if the ECM protects the engine from overheating.
Companion communication codes stored by related modules.

How to diagnose U019F

A typical diagnostic flow when this code is present.

  1. 1
    Retrieve all DTCs and freeze-frame data; note any temperature or cooling-related codes stored with U019F.
  2. 2
    Monitor live coolant temperature and stop driving if it rises toward the overheat range.
  3. 3
    Test and load the battery and verify charging voltage before further diagnosis.
  4. 4
    Verify supply voltage and ground at the coolant pump control module connector.
  5. 5
    Inspect the CAN wiring and connector to the pump module for damage, corrosion, or heat distress.
  6. 6
    Attempt direct scan-tool communication with the coolant pump module to confirm whether it is on the bus.
  7. 7
    If wiring and power check good and the module is absent from the bus, replace and program the coolant pump control module per the manufacturer procedure.

Related network codes

Frequently asked questions

What does the Engine Coolant Pump Control Module do?

It manages operation of the electric or electronically controlled coolant pump, adjusting flow to regulate engine temperature. The ECM commands it over the data bus and monitors its status.

Is it safe to drive with U019F?

It can be risky. If the pump defaults to reduced output, the engine may overheat. Watch coolant temperature closely and have the fault diagnosed promptly to avoid engine damage.

Could a weak battery set U019F?

Yes. Low voltage during cranking is a common cause of lost-communication codes because modules can reset or drop off the bus, so test the battery and charging system first.

Does a replacement pump module need programming?

On many vehicles yes. A new module that has not been configured to the vehicle may not communicate correctly, leaving U019F set even though the hardware is good.

Disabling U019F in software

RaceTune can permanently disable U019F — 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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