BMW fault CF12 - Engine torque alive signal
U114A · Alive signal failure
CF12 is stored by the EGS when the alive counter in the engine torque message from the DME or DDE stops incrementing. The EGS monitors this CAN message to coordinate shift timing, torque converter lockup, and transmission protection strategies. The alive counter proves the data is being actively updated. When it stalls, the EGS knows the message is stale or the engine management module has stopped transmitting.
The EGS monitors the alive counter in the torque 1 CAN message broadcast by the DME (gasoline) or DDE (diesel). This monitoring runs when battery voltage is between 9V and 16V, terminal 30 is on, and CAN communications are otherwise OK. The MIL illuminates on the first drive cycle (ID 419).
- Module
- EGS
- Severity
- Warning
- Likely cause
- DME or DDE fault preventing torque message broadcast
- Common fix
- Diagnosing and resolving the engine management fault
Symptoms
- MIL (check engine light) illuminated on the first drive cycle.
- Harsh or poorly timed shifts because the EGS cannot coordinate with engine torque output.
- Possible transmission failsafe mode.
- Reduced shift quality with abrupt or delayed gear changes.
Common causes
- DME or DDE has an internal fault and has stopped broadcasting the torque message on the PT-CAN bus.
- PT-CAN bus wiring fault between the DME/DDE and EGS.
- Intermittent CAN bus error from a loose connector, damaged wire, or poor termination.
- Low battery voltage causing CAN bus communication instability.
Diagnosis
- Read the DME/DDE fault memory. The root cause is almost always in the engine management system. If the DME/DDE has internal faults or is in a reduced-function state, it may have stopped broadcasting the torque message. Resolve those faults first.
- Read all modules for CAN faults. If multiple modules report missing messages from the DME/DDE, the issue is either the DME/DDE itself or a PT-CAN bus problem. If only the EGS reports this fault, check the CAN wiring between the two modules specifically.
- Check battery condition. Measure resting voltage (at least 12.4V) and perform a load test. CAN communication errors are a common symptom of low battery voltage.
- Inspect PT-CAN wiring between the DME/DDE and EGS for damage. Measure bus resistance at an accessible point: should read approximately 60 ohms with ignition off.
- If DME/DDE faults are present, the torque message fault in the EGS will resolve once the engine management system is operating normally again.
Resolution
Diagnose and resolve any DME/DDE faults first, as this is the most likely root cause. Repair PT-CAN wiring if damaged. If the DME/DDE module is faulty, replace and program using ISTA. Clear faults in both EGS and DME/DDE after the repair, then road test and verify the MIL does not return and shift quality is restored.