The 7G-Tronic (722.9) automatic transmission installed in Mercedes vehicles is the successor to the five-speed 5G-Tronic. This type of gearboxes is characterized by the fact that instead of classic gears, they have planetary gears. The box can also be operated manually. It has been produced since 2003 and, depending on the variant, can transmit up to 850 Nm. Four-wheel drive can also be used. Therefore, it is ideal for larger Mercedes cars. The construction of this gearbox allows for unprecedented smoothness of gear changes, outclassing all the competition. Only CVTs are smoother, but as we know, they are continuously variable.
One of the faults that we may encounter in the 7G-Tronic gearbox are errors in the speed sensors Y3/8n1, Y3/8n2, Y3/8n3, which control the gearbox drive. They are mainly caused by the poor condition of the hydraulic oil that works in the gearbox. If we neglect to replace it systematically, we are asking for a breakdown. The controller is damaged by incorrect readings of information from dirty sensors.
Symptoms of such damage may include:
- After the engine warms up, the gearbox enters emergency mode
- Turbine speed sensor errors
- Solenoid valve errors, sensor error
- The box doesn't work, you can't move
- Incomprehensible RPM signal from the sensor signal disturbed
- The box is jerking
Errors:
- 0717 / 0718 - Y3/8n1 - Rotation speed sensor 1
- 0722 / 0723 - Y3/8n2 - Rotation speed sensor 2
- 2766 / 2767 / 2768 - Y3/8n3 - Rotation speed sensor 3
- 2204 - Signal from component Y3/8n1 (turbine speed sensor (VGS)) is unavailable
- 2205 - Element Y3/8n1 (turbine speed sensor (VGS) is damaged
- 2200 - Signal from component Y3/8n2 (internal speed sensor (VGS)) is unavailable
- 2201 - component Y3/8n2 (internal speed sensor (VGS)) is damaged
- 0642 - The power supply voltage of the speed sensors is damaged