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Autotuner has added two Bosch petrol ECUs to its OBD list: the MED17.1.21 and the MED17.1.27, both built around the TC1793 processor. The announcement is dated 2 November 2026 and is part of a major high-volume software update for the AutoTuner One. The supplier lists OBD Virtual Read only for these two ECUs, and does not mention a bench or boot route.
Which ECUs
Both ECUs are Bosch MED17.1 variants with the TC1793 MCU, found on small-capacity Volkswagen Group TSI engines. The MED17.1.21 is listed against the 1.4 TSI engines, including the hybrid and GTE versions. The MED17.1.27 is listed against the 1.0 TSI and 1.0 eTSI engines, plus some 1.4 TSI GTE and hybrid applications.
The supplier quotes a write time of 11 minutes 30 seconds, with checksum correction and a back-to-stock function. It also notes that a Secure Gateway is present on these applications. Production years are not stated in the announcement, so check the ECU label before you quote a job.
Cars this opens up
MED17.1.21 (1.4 TSI and 1.4 TSI e-tron):
- Audi: A1, A3, A4, A5, Q2, Q3
- Volkswagen: Golf (1.4 TSI and GTE), Passat (1.4 TSI and GTE), Arteon Hybrid, Jetta, Polo, Tiguan, Touran, Sharan
- Seat: Leon, Ibiza, Ateca, Arona, Alhambra
- Skoda: Octavia, Superb (1.4 TSI and Hybrid), Kodiaq, Karoq
MED17.1.27 (1.0 TSI, 1.0 eTSI and some 1.4 TSI):
- Audi: A1, A3, Q2 (1.0 TSI/TFSI), Q3 (1.4 TSI)
- Volkswagen: Golf (1.0 TSI and 1.4 TSI GTE), Polo, Up! GTI, T-Cross, T-Roc, Taigo, Caddy, Passat, Arteon Hybrid, Nivus, Virtus, Taos
- Seat: Leon (1.0 TSI and 1.0 eTSI), Ibiza, Arona, Ateca (1.0 TSI)
- Skoda: Fabia, Scala, Kamiq, Octavia, Rapid, Karoq, Kodiaq (1.0 TSI), Superb Hybrid (1.4 TSI)
What it means
For owners, these are some of the most common small-engined cars on UK roads, and many of them are company or family cars that have never been looked at by a tuner. A good file for a 1.0 or 1.4 TSI typically gives a noticeable improvement in mid-range response, and the work is done through the OBD port rather than with the ECU removed. If you want to see what is possible on your own car, start with our tuning builder.
For dealers, an OBD route on volume ECUs like these means short job times and no bench work. The Secure Gateway note is worth reading before you take a booking on a newer car. If you run an Autotuner, see our Autotuner tuning tool page, and if you would rather send us the job, our file service is there for dealers.
