What Is RAB on a Subaru? Reverse Automatic Braking and the RAB Disabled Message
RAB on a Subaru means Reverse Automatic Braking. When you back up, sonar sensors in the rear bumper look for obstacles, warn you with beeps and can apply the brakes automatically to avoid or lessen a low-speed collision. A “RAB disabled” or RAB OFF indicator usually means the system was switched off, or the rear sensors are blocked by dirt, snow, ice or a bike rack. Clean the rear bumper sensors, remove anything covering them and restart the car. If RAB stays disabled with clean sensors, there may be a sensor or wiring fault that a Subaru dealer should check.
Subaru’s Reverse Automatic Braking is one of those features you forget about until it suddenly stops you in a parking lot, or until a “RAB disabled” message appears on a snowy morning. Knowing how it works and what turns it off makes it much less confusing.
This guide explains what RAB does, why it shows as disabled, how to turn it on or off, and when the warning needs a dealer.
What Is RAB on a Subaru?
Reverse Automatic Braking uses ultrasonic (sonar) sensors in the rear bumper to detect objects behind the car while you reverse at low speed. As you get closer, the car beeps faster. If a collision looks likely and you do not brake, RAB can apply the brakes automatically. It is available on many recent Outback, Forester, Ascent, Legacy, Crosstrek and Impreza models, often as part of an option package. It is designed for stationary objects like posts and walls and may not detect everything, so it is an aid, not a replacement for looking.
Why Does My Subaru Say RAB Disabled?
| Cause | What to do |
|---|---|
| Snow, ice, mud or road salt on the rear bumper | Clean the sensors gently with water and a soft cloth |
| Bike rack, cargo carrier or trailer hitch accessory | Remove it or switch RAB off while it is fitted |
| Towing a trailer | RAB may be unavailable. This is normal |
| RAB switched off by a driver | Turn it back on in the settings or with the switch |
| Heavy rain or extreme temperatures | Usually returns once conditions improve |
| Damaged sensor, bumper repair or wiring fault | Have a Subaru dealer diagnose it |
How to Fix a RAB Disabled Message
Look for a RAB OFF indicator. Depending on the model, RAB is turned on and off in the touchscreen settings or with a switch, so check that nobody turned it off.
Find the small round sensors in the rear bumper and wipe off dirt, snow and ice with water and a soft cloth. Avoid pressure washing them up close.
Take off bike racks, cargo carriers or stickers that cover or sit close behind the sensors.
Turn the car off and on again. The system often clears itself once the sensors can see.
If the message remains with clean sensors, or appeared after a rear bumper repair, have a Subaru dealer check the sensors, wiring and calibration.
How to Turn RAB On or Off
The method depends on the model year:
- Touchscreen models: with the shifter in Reverse, Subaru’s support pages describe on-screen buttons for turning RAB off. Most models also have an RAB setting in the vehicle or driver assist settings menu.
- Models with a switch: some have a RAB OFF switch on the dashboard or a setting in the instrument cluster menu.
- On many models RAB turns back on automatically the next time you start the car.
Step-by-step instructions are in our guides on how to turn on RAB on a Subaru and RAB on the Subaru Ascent. Subaru’s other driver aids include Auto Vehicle Hold.
- Wipe the rear sensors whenever you clean the backup camera lens.
- Turn RAB off when backing toward tall grass or a car wash track to avoid surprise stops.
- Tell your body shop the car has RAB before any rear bumper repair or paint.
- Never rely on RAB alone. Check mirrors and the camera every time.
RAB on a Subaru is Reverse Automatic Braking, which uses rear bumper sensors to warn you and brake automatically when reversing. “RAB disabled” usually means it was switched off or the sensors are dirty or blocked. Clean the sensors, remove any racks, check the settings and restart. If it stays disabled, have a dealer check for a sensor or wiring fault.
Subaru RAB FAQs
RAB stands for Reverse Automatic Braking. It detects obstacles behind the car when reversing and can apply the brakes automatically.
Usually because the rear sensors are covered by dirt, snow or ice, something like a bike rack is in the way, or the system was switched off.
Use the RAB setting in the touchscreen or cluster menu, or the RAB switch on models that have one. On many models it turns on again at the next start.
Yes. The car drives normally, but you lose the automatic braking aid when reversing, so take extra care.
In the rear bumper. They are small round sensors spaced across the bumper cover.
Generally it is not available when a trailer or hitch accessory blocks the sensors. Check your owner’s manual.
- RAB = Reverse Automatic Braking.
- Rear sonar sensors detect obstacles.
- “Disabled” = dirty sensors or switched off.
- Clean, remove racks, restart.
- Still disabled? Dealer check.