MED9.1 and MED9.5.10 immo off, original and stage 1 files for Golf V GTI, A3, Leon and Touareg

A Leon FR 2.0 TFSI comes in with 1P0907115 on the ECU sticker and a customer asking for stage 1. The same week a Golf 1.6 FSI with 03C906056BA won’t start after a used ECU was fitted. Two different Bosch boxes, MED9.1 and MED9.5.10, same shape, same connector, same processor family, and a lot of people file them under one name. They’re not the same job.

Which is which

MED9.1: the turbo FSI controller

MED9.1 runs the 2.0 TFSI (AXX, BWA, BPY, BWE) in Golf V GTI, Jetta, A3 8P, Leon FR and Cupra, Octavia RS and the Passat B6 2.0T. It also covers the bigger naturally aspirated FSI units: the 3.2 VR6 in the Touareg (03H906032), the 3.6 FSI in the Passat (3C0907115) and the 3.2 FSI V6 in the A6 C6 (4F2910115). Two MB of flash, MPC5xx processor, and a separate EEPROM for immo, VIN and adaptation values.

MED9.5.10: the small FSI controller

MED9.5.10 covers the 1.4 FSI (BKG, BLN) and 1.6 FSI (BAG, BLF, BLP) with 03C906056 numbers, and the 2.0 FSI (AXW, BLR, BLX, BLY, BVY) with 06F906056 numbers, in Golf V, Touran, A3, Leon and Octavia II. One MB flash on most versions, otherwise the same architecture.

Part numbers on our shelves

• SEAT LEON MED9.1 0261S02113 1P0907115 0040 1037386675
• SEAT LEON CUPRA MED9.1 0261S02337 1P0907115C 0020 1037386637
• VW TOUAREG MED9.1 0261S02355 03H906032S 1489 1037390200 (original and IMMO OFF)
• VW PASSAT MED9.1 0261S02510 1037391093 3C0907115S 0020 IMMO OFF
• AUDI A6 MED9.1 0261S02466 4F2910115F 0020 1037394380
• VW GOLF MED9.5.10 0261S02008 03C906056B 5401 1037368666
• VW GOLF MED9.5.10 0261S02070 03C906056BA 5697 1037369726 IMMO OFF
• VW GOLF MED9.5.10 0261S02071 03C906056AK 6095 1037370366 IMMO OFF
• AUDI A3 MED9.5.10 0261S02046 1037372517 06F906056CG 7001

OBD, BDM, and why there’s no boot mode

People ask for a boot-mode read on MED9 because they know it from EDC17 and MED17. MED9 doesn’t have one; that’s a Tricore feature. What MED9 has is BDM, the pad row on the board that KTAG, BDM100 and Flex read through. OBD read and write works for the flash on both units with KESS V2, MPPS or Galletto 4, and for a stage 1 that’s all you need. For immo off the ECU has to come out and go on the BDM frame, because the immobiliser data sits in the EEPROM and OBD tools only see the flash. Read flash and EEPROM together, keep the original, and send us the full dump. The OBD, bench and boot guide explains where the newer units differ.

What stage 1 actually gives

On the 2.0 TFSI with the K03 turbo, a sensible stage 1 takes 200 hp to about 240 and torque from 280 to around 330 Nm. Beyond that the K03 runs out of air, the diverter valve fails and the high-pressure pump cam follower wears faster. Check the follower before tuning a BWA with unknown history; it’s a ten-minute job and it saves a camshaft. On the MED9.5.10 naturally aspirated engines there isn’t much to gain. Five to eight percent from timing and lambda targets, a sharper throttle map, and that’s it. Be straight with the customer, or sell them the immo off they came in for and leave the tuning alone.

Immo off on a used ECU

These cars are Immo 3 or Immo 4 depending on year. The cheap route on a Golf V is to adapt the replacement ECU with VCDS or VCP; on later cars the login needs online access. When that isn’t available, an immo off file removes the handshake in the replacement ECU’s EEPROM and the engine starts. We need the EEPROM from the ECU that’s going into the car, not from the old one. It’s a repair option for a car with its own keys, not a bypass for a vehicle without them.

Two things to check first

A no-start on a MED9.5.10 FSI is very often the high-pressure fuel pump or a failed cam adjuster, not the immobiliser. Look at rail pressure in measuring blocks before you order anything. And on a MED9.1 that dies after a tune, check the N75 and the diverter valve before assuming the file is wrong; a split diaphragm gives exactly the same overboost fault as a bad map.

Stock and immo off versions by number are on the MED9.1 and MED9.5.10 pages, and the chip tuning category holds the stage 1 files for the TFSI units. If your number isn’t listed, send the BDM read through the request page with the software ID and we’ll match it.