Cause 1: Leaky clutch actuator (slave cylinder)
Diagnosis 1: Remove actuator and check for traces of oil, especially on the metal rod. Alternatively, lower the gearbox and check for oil traces in the clutch bell housing.
Solution 1: Replacement or repair of the clutch master – we offer overhaul / repair!
Cause 2: Defective dual mass flywheel (DMF), often as consequential damage to the actuator
Diagnosis 2: Check the play of the DMF, use manufacturer’s instructions
Solution 2: Exchange of the DMF
Diagnosis 1: Remove actuator and check for traces of oil, especially on the metal rod. Alternatively, lower the gearbox and check for oil traces in the clutch bell housing.
Solution 1: Replacement or repair of the clutch master – we offer overhaul / repair!
Cause 2: Defective dual mass flywheel (DMF), often as consequential damage to the actuator
Diagnosis 2: Check the play of the DMF, use manufacturer’s instructions
Solution 2: Exchange of the DMF
The gear symbol is the general fault message from the SMG and can have many different causes.
1. hydraulic pressure in the accumulator is too low
2. clutch cannot be actuated
3. switching / selection angle sensors provide implausible values
For further diagnosis, see detailed descriptions of the above problems.
1. hydraulic pressure in the accumulator is too low
2. clutch cannot be actuated
3. switching / selection angle sensors provide implausible values
For further diagnosis, see detailed descriptions of the above problems.
The SMG system based on hydraulics requires sufficient pressure in the pressure accumulator for shifting and clutch operations. The hydraulic pressure can be displayed as a live measured value in the diagnostic program Inpa or ISTA-D or in other professional testers.
Cause 1: Defective hydraulic pump
Diagnosis 1: The SMG does not create any hydraulic pressure. The pump cannot be heard when the car is unlocked or ignition switched on.
Solution 1: Replacement of the pump or pump motor. We offer the part in our shop.
Cause 2: Defective / worn pressure accumulator. The piston pressure accumulator has a nitrogen filling to generate the contra pressure, which can outgas within the lifecycle of the part.
Diagnosis 2: Observation of the pressure drop in the accumulator in the N-gear without any action. If the hydraulic pressure drops so quickly that the pump has to pump significantly more frequently than once per minute, the pressure accumulator is defective.
Solution 2: Replacement of the pressure accumulator. Please note: the pressure accumulator has a limited storage period, which is greatly reduced when stored in a dry place. Therefore it is best to use new parts!
Cause 1: Defective hydraulic pump
Diagnosis 1: The SMG does not create any hydraulic pressure. The pump cannot be heard when the car is unlocked or ignition switched on.
Solution 1: Replacement of the pump or pump motor. We offer the part in our shop.
Cause 2: Defective / worn pressure accumulator. The piston pressure accumulator has a nitrogen filling to generate the contra pressure, which can outgas within the lifecycle of the part.
Diagnosis 2: Observation of the pressure drop in the accumulator in the N-gear without any action. If the hydraulic pressure drops so quickly that the pump has to pump significantly more frequently than once per minute, the pressure accumulator is defective.
Solution 2: Replacement of the pressure accumulator. Please note: the pressure accumulator has a limited storage period, which is greatly reduced when stored in a dry place. Therefore it is best to use new parts!
Cause 1: Leak in hydraulic system
Diagnosis 1: Leaks result in leakage of oil. Therefore, external oil traces and the continuous loss of hydraulic oil in the expansion tank should be noticed.
Solution 1: Elimination of the leak by replacing or repairing the components. Often the clutch actuator (slave cylinder) leaks.
Diagnosis 1: Leaks result in leakage of oil. Therefore, external oil traces and the continuous loss of hydraulic oil in the expansion tank should be noticed.
Solution 1: Elimination of the leak by replacing or repairing the components. Often the clutch actuator (slave cylinder) leaks.
Cause 2: Defective / low-age pressure accumulator. The piston pressure accumulator has a nitrogen filling to generate the back pressure, which can outgas within the lifecycle of the part.
Diagnosis 2: Observation of the pressure drop in the accumulator in the N-gear without any action. If the hydraulic pressure drops so quickly that the pump has to pump significantly more frequently than once per minute, the pressure accumulator is defective.
Solution 2: Replacement of the pressure accumulator. Please note: the pressure accumulator has a limited storage period, which is greatly reduced when stored in a dry place. Therefore it is best to use new parts!