Mercedes-Benz W204 automatic transmission jerks when cold
W204 automatic jerks when cold, what causes it?
The cause varies from car to car and transmission to transmission. Possibilities are old transmission oil, incomplete clutch filling when cold, sticking or leaking valves, and a sensor or conductor plate fault. That is why the fault should be investigated with fault codes and the condition of the oil.
Does a software update or an oil change help with the W204's cold jerking?
In some cars a software update together with changing the oil and filter removed the jerking. For the jerks in the 1-2 and 2-3 shifts of the 722.9 transmission when cold, the manufacturer's bulletin specifically points to a software update. Old oil is also a common suspect.
What does teaching the transmission adaptations do?
The transmission learns shift values separately for the cold, warm and hot ranges. Teaching requires oil of at least 40 °C, so the cold-range values cannot always be taught. Simply resetting does not fix the fault and can make the situation worse; the teaching is a job for a workshop.
What is done if adaptation does not help a transmission that jerks when cold?
If the jerking continues, the operation of the torque converter lock-up clutch is examined, and the oil pan is checked for wear particles. Depending on the findings, the torque converter and oil or the electro-hydraulic control unit are replaced. A thermostat fault can also distort temperature data and cause jerking.