These instructions apply to the Audi A4 Mk5 (B9/8W) 2015-Present.
For other models, please choose your vehicle here.
The Audi A4 (B9, 2015–Present) — saloon, Avant, allroad and S4 — sits on the MLB-evo platform and uses an electronic parking brake with motor-driven rear calipers. To change the rear pads you must put the EPB into service mode with a scan tool so the rear actuators retract electronically. There is no owner-only button sequence on the B9 that opens the calipers, and HaynesPro flags the B9 brakes as needing a diagnostic tool for exactly this reason.
What Service Mode Is and Why You Need It
Each rear caliper has an electric motor that screws a spindle onto the piston to clamp the pads for parking. Thicker new pads will not fit until that spindle is wound fully back. Service mode commands both rear motors to retract, leaving the piston free to push home by hand with the caliper off the disc.
Use Ross-Tech VCDS, OBDeleven, or a generic £20–40 OBD EPB/SAS tool with a VAG “lining change / brake pad change” routine. The diagnostic socket is in the driver’s footwell. On the B9 the function lives under [53 — Parking Brake] → Basic Settings; some tools reach it via the ABS (03) module — use the tool’s pad-change menu and it picks the right path.
Retracting the Caliper
- Park level, ignition on, engine off, battery charger connected — the B9 EPB controller is very sensitive to low voltage and will abort mid-routine.
- Turn Auto Hold off and release the parking brake (cycle the EPB on then off once if prompted).
- Select Start lining change mode. The rear motors run and back the spindles off.
- Wait about 30 seconds after they stop, remove the caliper, and push the piston straight in by hand — no twisting.
Never Force the Pistons
Never clamp, wind or hand-force the rear pistons back on the A4 B9. The piston sits on the EPB motor’s spindle; forcing it strips the actuator gearbox or spindle thread and ruins the caliper — a costly mistake on this car. Only run open/close routines with the pads and caliper properly fitted to the disc, never with the brake disassembled. Let service mode retract the spindle electronically, then the piston pushes in with light, straight hand pressure only.
Exit and Bed-In
With new pads in and the caliper torqued, select End lining change mode. The motors re-clamp and take up clearance. Cycle the ignition, apply and release the EPB twice, and confirm the brake-warning light is out. Then bed in with several moderate stops from about 30–40 mph, cooling between them, before any hard braking.
Frequently Asked Questions
Does the A4 B9 need a diagnostic tool for rear pads?
Yes — the rear EPB motors must be retracted electronically, and HaynesPro lists the B9 as requiring a tool. A generic OBD EPB tool with a VAG pad-change routine is enough; you do not need a dealer machine.
My tool can’t open the EPB under module 53 — what now?
On some B9 builds the pad-change routine is reached through the ABS (03) module. Use the tool’s dedicated “brake pad replacement” menu, which selects the correct module.
Why is a battery charger so important here?
The B9 EPB is especially voltage-sensitive; a sag mid-routine can leave the calipers stuck open and throw a fault. Keep a charger on for the whole job.
Is the S4 / Avant / allroad the same?
Yes — all B9 variants use the same rear EPB motors and service-mode routine.
Parking-brake fault after the change?
Re-run End lining change mode to close the calipers fully, then clear the code. Decode any stored fault on autodtcs.com.
If an EPB or ABS warning stays on after the job and logs a code, look it up on autodtcs.com.
Independent guide — not affiliated with Audi. Always follow your official service manual and safety precautions. Read our full disclaimer.