Audi ECU Repair: Fixing Simos, MED17 & EDC17 Failures

Audi has relied for years on engine control units from Bosch and the VW Group's Simos system. Whether A3, A4, A6 or Q5: when the engine control unit fails, the vehicle is off the road — and the dealer quickly charges well over 1,500 euros for a new unit plus coding. In most cases a targeted repair of the original unit is the faster and significantly cheaper alternative.

Which Audi control units do we repair?

• Simos — petrol control units from the VW Group, used in the A3, A4 and Q3 among others (capacitor failures, communication drops)
• MED17 — Bosch petrol ECU in many Audi models (voltage regulator, power supply)
• EDC17 — diesel ECU in the A4, A5, A6, Q5 and others (injector drivers, driver stages)
• MG1 / MDG1 — current Bosch generations in newer models (diagnosis and repair after unlocking)

What we do not repair: ABS, airbag, transmission or other control units. We specialise exclusively in engine control units (ECU).

Typical defects in Audi engine control units

Capacitor failures (Simos)

The electrolytic capacitors in Simos control units age. Symptoms: sporadic starting problems, OBD communication drops, fault codes that return after clearing. Replacing the affected capacitors is a standard board-level repair.

Injector drivers (EDC17)

Cylinder-selective misfire, rough running, fault code on one cylinder — the injector nozzle is often suspected, but the driver IC in the control unit has actually burned out. A classic EDC17 defect.

Voltage regulators and power supply (MED17)

Defective voltage regulator or blown capacitors: the unit does not start or behaves unreliably. Typical for MED17 in combination with high mileage.

Water damage

Water ingress via the cowl panel is one of the most common causes of defects in the VW Group. Corroded boards are often repairable if detected early — cleaning, trace repair, sealing.

Audi ECU repair process

1. Incoming inspection — visual check, pin test, communication test (OBD/K-Line/CAN)
2. Fault location — defective component identified at board level
3. Repair — component replacement, soldering work, cleaning, sealing for water damage
4. Function test — load test before return shipment

Advantages over a new part

• Original unit retained — coding, immobiliser and adaptations remain fully intact
• No recoding — plug-and-play after refitting
• Faster — 2-3 working days processing time after receipt
• Cheaper — typically 50-70 % below the new-part price including coding

Send in your Audi control unit

Via our mail-in service (Control Unit Submit) you submit vehicle data, fault description and the part number of your Audi control unit. You will receive an initial assessment with a price range within one working day. Once approved, send in the unit — we handle diagnosis, repair and return shipment.

Whether Simos, MED17 or EDC17: if the engine control unit of your Audi is defective, we repair it — with a 12-month warranty on our work.