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Mercedes GLA X156 7G-DCT TCU Cloning by Post — Part Numbers A0054463310, A2C73939004 & A0054463710 | Fault Codes P1890 P1872 P17XX

Your GLA X156 is refusing to pull away cleanly, lurching between gears, or sitting there with a transmission warning light and a stack of fault codes — P1890, P1872 and a string of P17XX entries — stored in the gearbox control unit. Those codes point squarely at the 7G-DCT TCU: the transmission control unit has either corrupted its own data or failed outright, and the gearbox is protecting itself by limiting or refusing drive. The fix is TCU cloning — the data from your original unit is read and written onto a known-good replacement, so the new unit already knows your car when it goes back in.

The Vehicle Check clones 7G-DCT TCUs for the Mercedes GLA X156 by post, from anywhere in the UK. Post your unit in, and it comes back matched to your car — typically within 3–5 working days.

Quick Facts

What Are Fault Codes P1890, P1872 and P17XX Actually Telling You?

P1890 and P1872 on the GLA X156 indicate internal TCU faults — the control unit is flagging errors in its own clutch-engagement logic or internal communication pathways. The P17XX family covers a broader range of transmission ratio and speed-sensor plausibility errors that cascade when the TCU is struggling. Together they usually mean one thing: the TCU itself is the problem, not a mechanical gearbox failure. Replacing the unit is straightforward — but a straight swap without cloning leaves the gearbox unable to communicate properly with the rest of the car. Cloning carries the original calibration, adaptation and vehicle-specific data across to the replacement, so it's ready to run from the moment it's plugged in.

Which Part Numbers Does This Cover — and How Do I Check Mine?

The units TVC handles for the GLA X156 7G-DCT include A0054463310, A2C73939004 (5-pin connector variant) and A0054463710 (4-pin connector variant). These are unit-family reference numbers — the exact number printed on your own TCU label can vary by build date, supplier batch and market. Check the label on your unit before sending, and TVC will confirm whether it falls within the cloning scope before any work starts. Never assume a number matches just because it looks similar.

TVC has been working on Mercedes transmission electronics for years, alongside other complex mechatronic and electronic systems — from DSG and 9G-Tronic mechatronics to BCM and BSI cloning — which means the diagnostic and data-handling experience behind your TCU clone is built on a wide base of real automotive electronics work, not guesswork.

How Does Mail-In TCU Cloning Work — Step by Step?

The process is straightforward and doesn't require a dealer or a local specialist at any stage.

1. Call ahead: Ring 0203 489 2610, confirm your part number and fault codes, and TVC will advise on anything specific to your unit before you remove it.
2. Remove the TCU: The 7G-DCT TCU is accessible without removing the gearbox. If you're not confident doing this yourself, any independent mechanic can remove it for a small labour charge — far less than a dealer workshop visit.
3. Pack it properly: Wrap the unit in bubble wrap or foam padding — no loose rattling inside the box. Use a sturdy cardboard box and fill any gaps. Use a tracked, insured service (Royal Mail Special Delivery or a named courier). Write the TVC address clearly: Office 13, 25 Mollison Avenue, Enfield, EN3 7NJ.
4. TVC clones it: Your original unit's data is read and transferred to a compatible replacement. Turnaround is 3–5 working days from receipt.
5. Free return: The cloned unit is returned to you by free tracked courier. Refit it, do a basic adaptation reset with a scan tool, and clear the fault codes.

Mail-In vs Mercedes Dealer — Honest Comparison

What Else Does TVC Handle for Mercedes and Other Makes?

The GLA X156 TCU clone sits within a broader capability. TVC also handles Mercedes 9G-Tronic mechatronic repair and cloning, clutch actuator repair, SRS airbag module crash data reset and much more — all by the same nationwide mail-in route. If your GLA has more than one fault, it's worth asking whether a combined send makes sense.

Frequently Asked Questions

Ready to Send Your GLA X156 TCU?

If your Mercedes GLA X156 is storing P1890, P1872 or P17XX codes and you've confirmed a TCU fault, the next step is straightforward. Call The Vehicle Check on 0203 489 2610, quote your part number (A0054463310, A2C73939004 or A0054463710), and TVC will confirm scope and walk you through packing and postage. Send to Office 13, 25 Mollison Avenue, Enfield, EN3 7NJ. Turnaround is 3–5 working days and return shipping is free.

Can't get through by phone? Use the contact form at thevehiclecheck.co.uk/collections/mechatronic and TVC will get back to you promptly.

The Vehicle Check is a UK automotive electronics specialist at Office 13, 25 Mollison Avenue, Enfield, EN3 7NJ, offering nationwide and international mail-in repair and cloning. Call 0203 489 2610. Last updated: 10 November 2026.