How do you bleed air from ABS brakes?

Air in ABS brakes can compromise pedal feel and stopping power. Bleeding typically follows the standard wheel-bleed sequence and, if air remains trapped in the ABS modulator, you perform an ABS bleed with a scan tool or by following the manufacturer's procedure. This guide walks you through safe, accurate steps and cautions to help you do it right.

What you need to know

Bleeding an ABS-equipped system adds a layer of complexity beyond a conventional brake bleed. You usually bleed the conventional lines first, then address the ABS module if air is still present. Always consult the vehicle’s service manual for the exact wheel order, fluid type, and any model-specific ABS procedure.

Tools and materials

Gather the following so you can bleed efficiently and with less risk of reintroducing air.

• Correct brake fluid (DOT grade as specified by the vehicle manufacturer), in a clean bottle


• Brake fluid compatible bleed kit (clear tubing, catch bottle, clamps)


• Wrenches or sockets to fit each brake bleeder screw (usually 8–10 mm)


• Transparent hoses to observe air bubbles


• Two-person helper (pedal press) or a quality vacuum/pressure bleeder


• Funnel or adapter for the master cylinder reservoir


• Brake cleaner and rags for spills


• Jack stands, wheel chocks and proper PPE (gloves, eye protection)


• Vehicle service manual or manufacturer bleed procedure (for ABS-specific steps)

Having the right tools helps avoid contamination and ensures you can follow the exact bleed pattern your vehicle requires.

Step-by-step bleed procedure

Use this common approach as a baseline. Always defer to your vehicle’s manual for the exact wheel order and any ABS-specific instructions. If your model supports an ABS bleed function with a scan tool, use it after the wheel bleeding ends.

1. Prepare the vehicle. Park on a level surface, chock wheels, engage parking brake, and ensure the master-cylinder reservoir is clean and full with the correct fluid. Do not let the reservoir run dry during bleeding.


2. Choose the bleed sequence. The typical order is to start with the wheel farthest from the master cylinder and work toward it; common sequences are RR → LR → RF → LF, but verify with the manual for your car.


3. Attach the bleed hose to the first caliper’s bleeder screw and submerge the hose in the catch bottle filled with a bit of brake fluid to prevent air from re-entering.


4. Have your helper press the brake pedal slowly to the floor and hold it there; loosen the bleed screw to allow fluid (and air) to escape, then close the screw before the pedal returns. Repeat until the freed fluid runs clear of air bubbles.


5. Move to each wheel in order, topping fluid in the reservoir as needed and keeping the level above the minimum to prevent new air ingress.


6. When you reach the last wheel, re-check pedal feel. If the pedal still feels spongy, you may need to perform an ABS-specific purge.


7. ABS purge (if required). If a service procedure or scan tool indicates, engage the ABS bleed function or cycle the ABS pump as directed by the manufacturer. This may involve using a scan tool to command the pump/modulator to cycle several times or performing a controlled ignition-cycle to energize the pump in some models.


8. Finish and test. Refill the reservoir to the proper level, reinstall the cap, lower the car, and test the brakes at low speed in a safe area to verify firm pedal and absence of pulling or brake noise.

In practice, the ABS purge step is model-specific. If air remains after wheel bleeding, follow the manufacturer’s ABS bleed procedure or consult a professional to avoid compromising braking performance.

ABS-specific considerations

ABS systems can trap air differently depending on the vehicle. Some models require a dedicated ABS bleed procedure that can only be performed with a compatible scan tool. Others may require cycling the ignition to energize the pump or performing a pump-activation sequence after each wheel bleed. Always consult the service manual for your model and, if in doubt, have a professional bleed performed to avoid compromising braking performance.

• Do not mix brake fluids; use the exact DOT specification; poor-fluid choice can damage seals and the ABS pump.


• Keep the reservoir capped when not bleeding to avoid moisture intrusion or dirt contamination.


• Brake fluid is corrosive to paint; clean spills promptly.


• Bleed brakes with the engine off for manual pedal operations. For ABS pump cycling, the engine or ignition may need to be on per the manual.


• If ABS warning lights illuminate after bleeding, there may be a fault in the ABS module or wheel speed sensors requiring diagnostic testing.

Summary

Bleeding air from ABS brakes involves standard wheel bleeding plus an ABS-specific purge when air remains in the ABS module. Follow the wheel-bleed order appropriate for your car, monitor the brake-fluid level, and use a dedicated ABS bleed procedure if your vehicle supports it. When in doubt, consult the service manual or seek professional help to ensure safe, effective braking performance.

Can you bleed ABS without a scan tool?

Yes, you can bleed ABS brakes without a scan tool, but it requires extra steps to cycle the ABS module, and the process can vary by vehicle. First, perform a standard brake fluid bleed at the wheels. Then, to purge air from the ABS module, you must activate the ABS by driving the vehicle and stomping on the brakes to force an ABS stop. After activating the system, bleed the brakes again and test to confirm all air is out. 
Step 1: Activate the ABS 

• Drive the vehicle to a safe area, like an empty street or gravel lot. 
• Drive at a speed of about 20–30 mph. 
• Slam on the brakes to force the ABS to activate. 
• You may need to do this several times to fully cycle the ABS. 

Step 2: Perform a standard brake fluid bleed

• If your vehicle has a bleeder screw on the ABS module, bleed it first, starting with the front bleeder screw, as shown in this Tomorrow's Technician article. 
• Bleed the rest of the wheels in the correct order for your vehicle, which is typically: right rear, left rear, right front, and left front. 
• Use the traditional two-person method (one person pumps the pedal while the other opens and closes the bleeder screw) or a vacuum bleeder. 

Step 3: Repeat and confirm

• After the initial bleed, take the vehicle for another drive and activate the ABS again. 
• Return to the car and bleed all the brakes one more time to remove any air that was moved into the lines during ABS activation. 
• Test drive the vehicle again to ensure the pedal feels firm and the ABS functions correctly. 

Is there a special way to bleed ABS brakes?

What If You Don't Have a Dealer Service Tool? If you don't have access to a dealer-grade service tool, here's an alternative: In a controlled environment, engage the ABS system by braking hard enough to activate it. This simulates ABS cycling and pushes old fluid out of the hidden chambers.

Can air be trapped in an ABS module?

Some vehicles require a scan tool to activate the ABS pump. This tool circulates the fluid and dislodges air trapped within the ABS module.

How to get air out of ABS brake system?

To get air out of an ABS system, you can use a professional scan tool to activate the ABS module for a "modulator bleed" and then perform a standard manual brake bleed, or you can manually bleed the system and then use the vehicle's momentum to activate the ABS by driving and slamming on the brakes. 
Method 1: Using a scan tool (recommended)

1. Prepare the system: Check the master cylinder fluid level and top it off with the correct brake fluid. 
2. Connect the scan tool: Plug the scan tool into the vehicle's OBD-II port and navigate to the "Brake Bleed" or "ABS Bleed" function. 
3. Follow the tool's instructions: The tool will guide you through the process, which typically involves opening and closing bleeder valves at each wheel as instructed while the tool activates the ABS pump. 
4. Repeat as needed: The process may need to be repeated to ensure all air is purged from the system. After the tool-assisted bleed, it's a good practice to perform a final manual bleed to be certain, according to YouTube. 

Method 2: Manual bleeding and ABS activation

1. Perform a standard brake bleed: With an assistant, bleed the brakes like you would a non-ABS system, starting from the wheel furthest from the master cylinder. 
2. Monitor fluid level: Keep the master cylinder reservoir from running dry during the process. 
3. Activate the ABS: Once the manual bleed is complete, drive the vehicle to a safe, open area like a dirt road or a slippery surface. 
4. Apply hard braking: Drive at a moderate speed and then slam on the brakes to engage the ABS. You should feel the pedal pulse and the system will work to push any remaining air through the lines. 
5. Check the pedal: The brake pedal should feel firmer after the ABS has been engaged. You may need to repeat the manual bleed and ABS activation steps if the pedal remains soft. 

Important considerations

• Safety first: Have ample space to stop when activating the ABS. 
• Risk: Driving with air in the brake system can compromise braking performance, so drive cautiously. 
• Scan tool vs. manual bleed: A scan tool is the most effective way to bleed an ABS system because it can activate the pump and valves inside the ABS module. The manual method is a good alternative if a scan tool is unavailable, but may not be as effective at removing air from the ABS modulator itself.