Description
Common Problems
The C123EF0 fault code appears on Audi, Porsche and Volkswagen vehicles fitted with Bosch ESP9-family ABS pump systems. When this fault occurs, the ABS warning light may illuminate and the traction control light may also come on. Drivers may see brake system warnings such as ‘Brake system fault stop carefully’ or related hydraulic brake booster pressure faults.
This fault can affect ABS and stability control operation. The vehicle may revert to reduced braking assistance or standard braking only, which lowers safety during emergency braking, wet roads, or sudden manoeuvres. The ABS pump/module should be correctly diagnosed and repaired rather than replaced unnecessarily.
Vehicles & Part Numbers Covered
Select your vehicle from the dropdowns above (or enter your registration) and the matching part numbers will be confirmed automatically. Part numbers vary by vehicle specification, so always confirm the number from the ABS pump/module label or diagnostic scan before ordering.
| Make | Model | Years | OEM Part No. | Bosch / Ref No. |
|---|---|---|---|---|
| Audi | A4 | 2015-2019 | 8W0907379G | 0265956241 |
| Audi | A5 | 2016-2019 | 8W0907379G | 0265956241 |
| Audi | A6 | 2017-2022 | 4K0907379P | 0265956621 |
| Audi | A7 | 2018-2020 | 4K0907379M | 0265956621 |
| Audi | A8 | 2017-2022 | 4N0907379 | 4N0614517 |
| Audi | Q5 | 2016-2020 | 80A907379E | 0265956241 |
| Audi | Q7 | 2015-2018 | 8W0907379J | 0265956241 |
| Audi | Q8 | 2018-2022 | 4M0907379 | 4M0614517 |
| Audi | S4 | 2016-2018 | 8W0907379G | 0265956241 |
| Audi | S5 | 2016-2018 | 8W0907379J | 0265956241 |
| Audi | SQ5 | 2017-2020 | 80A907379B | 0265956658 |
| Audi | SQ7 | 2016-2019 | 8W0907379F | 0265956312 |
| Porsche | Cayenne | 2018-2023 | 9Y0907379 | 9Y0614517 |
| Volkswagen | Touareg | 2018-2023 | 760907379 | 760614517 |
Our Repair Service
Send your original ABS pump/module to Essex Recons and we will test, repair and return it. Repairing the original unit helps avoid coding and programming issues that can occur when fitting a used replacement module.
Typical symptoms linked with this repair include:
- C123EF0 fault code stored in the ABS / brake electronics module
- ABS and traction control warning lights on
- Brake system warning message
- Hydraulic brake booster pressure fault
- Reduced ABS, ESP or emergency braking assistance
If you are unsure whether this is the correct listing, contact us with your vehicle registration, fault code and ABS pump part number.