BMW G20 Front & Rear Brake Pad Replacement
A satisfying DIY that saves a lot over the dealer — with one modern twist. The fronts are straightforward, but the rears have an electronic parking brake built into the calipers, so they must be put into service mode before you touch the pistons. Here's how to do all four corners properly.
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The G20 brakes are simple mechanically, but the rear is where people get caught: the parking brake is no longer a cable — it's an electric motor on each rear caliper. Try to wind or push the rear pistons back with the system live and you can damage the actuator. Put it into service mode first and the job is easy. The fronts have no such system, so they're a classic pad-and-rotor swap.
Parts & Tools You'll Need
Pads and rotors per axle, the wear sensor, and a tool for the rear EPB.
Step-by-Step
Loosen, Raise & Remove the Wheels
Crack the wheel bolts, raise the car and support it securely on stands, then take the wheels off. Work one axle at a time so you always have a reference.
Put the Rear EPB Into Service Mode
Before touching the rear calipers, connect the scan tool and activate the electronic parking brake service/retract function. This backs off the motors so you can safely retract the pistons. Do this first — it's the whole trick to the rears.
Front: Remove the Caliper & Retract the Piston
Undo the caliper guide bolts, lift the caliper off and support it (don't hang it by the hose). Push the front piston straight back into its bore with a clamp or spreader — no service mode needed up front.
Front: Swap Pads, Rotor & Sensor
Remove the carrier if replacing the rotor, fit the new rotor, then the pads (grease the contact points), and the new wear sensor if it's the front one. Reassemble and torque the caliper and carrier to spec.
Rear: Remove the Caliper & Retract the Piston
With the EPB in service mode, undo the rear caliper and retract the piston as the caliper requires (press straight in, or wind in if specified). Support the caliper as before. Forcing it without service mode risks the EPB motor.
Rear: Swap Pads, Rotor & Sensor
Fit the new rear rotor, pads and the rear wear sensor if applicable, grease the contact points, then reassemble and torque everything to spec. Repeat front and rear on the other side.
Reactivate the EPB & Pump the Pedal
Use the scan tool to take the parking brake out of service mode and reactivate/calibrate it. Then pump the brake pedal until it's firm so the pads seat against the rotors — never drive until the pedal is solid.
Reset Service, Bed In & Test
Reset the brake item in the iDrive Condition Based Service menu, refit the wheels and torque the bolts. Then bed in the new brakes with a series of moderate stops from speed, and test the parking brake holds.
Rear EPB must be in service mode first
The rear parking brake is an electric motor on the caliper, not a cable. Retracting the rear pistons without first putting the EPB into service mode can damage the actuator — an expensive mistake. Always set service mode before the rears, reactivate it after, and pump the pedal firm before driving.
Quick Specs
General guidance — verify for your exact car and brake variant.
| Item | Detail |
|---|---|
| Front | Standard pad/rotor swap — piston pushes straight in, no service mode |
| Rear | Electronic parking brake — service mode required before retracting |
| Wear sensor | Replace with pads (front, rear or both, by car) |
| M Sport / M340i | Larger discs — match the parts to the variant |
| After | Reactivate EPB, pump pedal, reset CBS, bed in |
FAQ
Do I need a scan tool for the rear brakes?
Effectively yes. The rear electronic parking brake must be put into service mode to retract the pistons safely, which needs a scan tool with the EPB function (or, on some cars, an iDrive service routine). The fronts don't need one.
Can I do just the fronts without the tool?
Yes — the front brakes have no electronic parking brake, so you can replace front pads and rotors with just a piston clamp. You only need the EPB service function when you do the rears.
Should I replace the wear sensor?
Yes — once a brake wear sensor has triggered it's a one-time part, so fit a new one with the pads. Check whether your car uses a front sensor, a rear one, or both.
Do M Sport and M340i brakes differ?
They do — M Sport and M340i cars run larger discs (and sometimes different calipers), so order pads and rotors for that specific variant rather than the base brakes.
How do I bed in the new brakes?
After pumping the pedal firm, do a series of moderate stops from moderate speed, letting the brakes cool between them, to transfer an even layer of pad material onto the rotors. Avoid hard stops or sitting on the pedal while everything's fresh.
You're Done
Fresh brakes all round — the easy fronts and the rears done right with the EPB in service mode, the wear sensor replaced, the parking brake reactivated and everything bedded in. The one rule to remember: never retract the rear pistons without service mode. Keep up the rest with the oil change and head back to the G20 hub.