To send a control unit in for repair, note the part number from the housing label, remove it and pack it in a sturdy box with at least 5 cm of padding on every side. Add a fault description and your contact details, plus a key or ring antenna for immobilisers. We test it and repair only after you approve.
This guide explains how sending a unit in works at Elektro Tech KFZ-Meisterbetrieb GmbH in Nettetal, Germany. Most of it applies to any reputable control unit repairer: know the part number, pack it safely, and you save yourself follow-up questions and days of waiting.
The short version in five steps
- Note the part number and photograph the label.
- Call us or send an enquiry so we can tell you up front whether the repair is worth it.
- Remove the unit, using a garage for complex components.
- Add what we need: fault description, contact details, return address and, where relevant, a key or ring antenna.
- Pack it firmly with at least 5 cm of padding and send it as a tracked parcel.
Where do I find the control unit part number?
The part number is on the label of the housing, usually on top or next to the connector. Many units carry several numbers: the vehicle manufacturer's part number (the OEM number) and the number of the supplier that built the unit, such as Bosch, Continental or Siemens. Note them all and take a sharp photo of the whole label.
If the label is faded or damaged, a diagnostic tool often helps: many control units report their part number in the identification data of a diagnostic scan. Garage invoices often list it too. With the number you can check our part search to see whether your component is already in the catalogue. If it is not, ask anyway.
Is the repair worth it? Call first
With the part number and the fault symptoms we can often tell you before you send anything whether a repair makes sense. A short call on +49 2153 9564711 (Monday to Friday, 9:00 to 16:00 German time) or a repair enquiry is enough. We usually answer enquiries within one working day, in German or English.
Many repairs have a price that is fixed in advance. If the fault is not clear-cut, we test the unit first and send you a quote. You then decide whether we go ahead.
Do I have to remove the control unit myself?
Yes, we need the unit itself, not the vehicle. Many owners can remove easily accessible units on their own. Disconnect the battery first and pull connectors by their locking tab, never by the cable. For more complex components such as gearbox mechatronics, ABS hydraulic units or immobilisers, we recommend having a qualified garage remove it, which also takes care of refitting it properly afterwards.
What goes in the box?
The more complete the information, the faster the diagnosis. Include:
- the part number (OEM or supplier number), if it is hard to read on the unit,
- a fault description: what happens, since when, and any fault codes that were read out,
- the make, model and year of the vehicle,
- your name, phone number, email and return address,
- extra parts if needed. For immobilisers and comfort control units we often need a key or the ring antenna. If in doubt, ask first. More on the immobiliser repair page.
If you sent an enquiry beforehand, add a printout or at least the enquiry details so the parcel can be matched straight away. Without a clear match and complete details we cannot start work.
How do I pack a control unit properly?
Control units are sensitive to knocks and electrostatic discharge. To get yours here intact:
- Use a sturdy box, not a thin or already damaged one.
- Pad it with at least 5 cm on every side, using bubble wrap or foam. The unit must not move inside the box.
- If you have an anti-static bag, put the unit in it first.
- Do not tape over the connectors. The residue causes contact problems later.
- Send it as a tracked parcel and keep the tracking number.
What happens once the parcel arrives?
Every unit goes through the same process, and no work starts until you have agreed to it.
| Step | What we do | Your part |
|---|---|---|
| 1. Testing | Technical test and fault analysis on the test bench | Nothing, we get in touch |
| 2. Offer | Fixed price or quote, depending on the fault | You decide |
| 3. Repair | Repair once you approve | Give approval |
| 4. Function test | Testing the repaired unit | Nothing |
| 5. Return | Packed and sent back with tracking | Refit it (or have it refitted) |
If the fault cannot be fixed, you pay no repair costs. Standard repairs are usually done within a few working days. For more involved faults we give you an expected timeframe once the unit has been tested.
Common mistakes when sending a unit in
- Without a part number and description we cannot match the unit and have to ask first.
- With too little padding, transport damage can turn a repairable unit into scrap.
- If the key or ring antenna is missing, an immobiliser often cannot be fully tested.
- Without a return address or phone number we cannot reach you for approval or send the unit back.
Not sure whether we handle your component? See all unit types under services.