TCU / TCM
Gearbox in limp mode? Often it’s the electronics.
Before you buy a replacement gearbox: we check whether the transmission control is the cause and repair it where possible.
Typical symptoms
- Gearbox stays in limp mode, often in a single gear
- Harsh, delayed or missing gear changes
- “Visit workshop” message or transmission warning on the display
- Fault codes for the transmission control or speed sensors
- Faults that only appear once the gearbox is warm
What causes it?
In many automatic gearboxes the electronics sit directly in or on the gearbox and work at high temperatures. Heat, gearbox oil creeping into connectors and wires, and ageing components lead to failures over time.
Sometimes only a sensor, connector or wire is affected. Electronics is our specialty: we tell you whether the transmission control is the reason – before you spend money on a replacement gearbox.
Focus on Mercedes-Benz. AEZ is an independent master workshop; brand names are used for description only. We tell you whether a repair is possible after testing.
How the repair works.
- 1
Get in touch
Vehicle, VIN and what happened – via WhatsApp, phone or form.
- 2
Drop off or send in
Hand it in at Bottrop or, after a quick chat, send it by DHL. How shipping works
- 3
Test, price, repair
You get the findings and price before we repair. Then the unit goes back to you.
Frequently asked questions
Is it the gearbox or the electronics?
That can usually only be said for sure after diagnostics and testing. Tell us when the fault occurs and which codes are stored – then we can test in a targeted way.
How much does the repair cost?
That depends on the unit and the fault. After testing we tell you the price – we only repair with your approval.
Can I send the control unit in?
Yes. After a quick chat, by DHL to AEZ, Werkstraße 4, 46240 Bottrop, Germany. Packing tips and the shipping note to fill in are on the “Sending in a control unit” page.
Do you only work on Mercedes-Benz?
Our focus is Mercedes-Benz. For other makes, just ask with the vehicle and part number – we’ll tell you honestly whether we can help.