Mercedes ABC Suspension Fluid Type, DIY Flush

If (Active Body Control) ABC light is ON or is flashing, there is a good chance your suspension system may be low on hydraulic fluid. When the ABC fluid level gets too low, you may also notice a humming or whining noise from the engine. Minor suspension oil leaks can develop on high mileage Mercedes-Benz and may require topping the hydraulic suspension once a year.

In this guide, we cover the following:

Mercedes Hydraulic Suspension ABC Fluid Type
How to check the ABC fluid level and
How to perform Mercedes ABC fluid flush.

Mercedes uses hydraulic suspension in many models, including S-Class, CL-Class, SL-Class, E-Class, etc. Mercedes-Benz cars with Active Body Control (ABC) suspensions use hydraulic fluid. It should NOT be confused with Airmatic suspension, which uses compressed air.

Mercedes ABC Fluid Type

The fluid type that is installed at the factory is Mercedes-Benz Hydraulic Oil Q 1 32 0001 manufactured by Pentosin.

If you like saving money, the Pentosin CHF 11S is the same as Mercedes-Benz Hydraulic Oil Q 1 32 0001. It is printed on the Mercedes ABC container as well.

Note that this hydraulic fluid is also often used in power steering systems.

How to check Mercedes Hydraulic ABC Fluid Level

Get at least two quarts of Pentosin CHF 11S.

No special tools are required to check Mercedes ABC fluid level. You will need a clean rag, and make sure to use gloves.

Turn off the engine and locate the ABC reservoir in the engine bay.
Remove the dipstick.
- The dipstick has two sides. One is for checking the hydraulic level fluid with the engine off, and one with the engine on.
  - Engine On – MOTOR AN UNBELADEN
  - Engine Off – MOTOR AUS UNBELADEN
Wipe off the dipstick.
- Note the side that says “MOTOR AUS UNBELADEN.” Since we are checking the level with the engine off, we will use this side.
Fully reinsert the dipstick into the reservoir and pull it out.
Read the level on the dipstick.

How to flush the Mercedes hydraulic system?

In this section, you will find instructions on how to flush the Mercedes-Benz ABC suspension yourself. Doing the work yourself can save you hundreds compared to having the dealer or a mechanic do the flush. The ABC system would run between $580-$800 at the dealer flushing.

What you will need

AGA Mercedes ABC Tool – OPTIONAL (eBay Link)

AGA tool is not required but can make the job easier on W221 and W216. Flush can be done without the tool. This tool also does not work on W220.

10 quarts of ABC Fluid: Pentosin CHF 11S

Gloves, Glasses, Screwdrivers, Clean bucket

Important

Wear gloves and glasses when changing Mercedes ABC fluid.
Do not allow fluid to fall on your vehicle paint.
It is important to work in a clean environment. No particles or dirt should be introduced to the ABC system.
The recommended method is to use Star Diagnostic and activate the ABC system to warm it up. Go to ABC Body Control > Actuation > Activate Rodeo mode to bring the temperature of the ABC system to 80 degrees Celsius. If you don’t drive Star Diagnostic, drive the vehicle for 30 minutes to warm up the ABC system.

Instructions

Drive the vehicle for at least 30 min or more. While driving, press the ABC button several times to engage the ABC pump. This will warm up ABC fluid, which is recommended.
Turn off the engine.
Remove the bracket on top of the ABC reservoir. ABC reservoir is located in the engine bay, behind the driver’s side headlight. You will need to remove the large bolt and then slide the bracket. This will give you enough room to remove the cap.
Remove the large cap on top of the ABC reservoir. The cap has the filter integrated below the lid. Keep a pan next to the ABC reservoir to collect ABC fluid that will drip from the filter.
Once the cap and filter are removed, the next step is to insert the AGA tool into the ABC reservoir and press it in. If you are not using the AGA tool, disconnect the return line into the ABC reservoir and route with an extension to a clean bucket that can hold at least 10 liters (or quarts).
Connect a clear hose to a container holding at least 10 quarts (or litters).
If you are using start, go to ABC COntrol Unit > Acuations > Cyclically alternating actuation of the front and rear suspension struts (pitch) >F3. If Star Diagnostic is unavailable, use the ABC switch in the dashboard and cycle it on and off every 5 seconds.
Open all your ABC fluid containers and get them ready. The fluid level on the ABC reservoir goes down quickly. You should not let the reservoir get empty.
Start the engine.
Have a friend cycle the ABC on and off every 10 seconds.
As the ABC fluid level goes down, add ABC fluid. Do not let the system go to MIN.
Once you have added 10 quarts of fluid, stop the engine.
Replace the filter and install it.
Check the ABC level. Add or remove fluid as needed.

Replace ABC Filter

You will need a new Mercedes-Benz Hydraulic Self-Levelling Oil Filter W/ ABC Genuine Original 0031846101.

The ABC filter is mounted on the ABC reservoir cap.
To change the ABC filter, remove the ABC cap.
Twist the filter and housing counterclockwise to unlock it from the cap.
Remove the filter from the housing.
Insert the filter into the housing.

Additional Resources

Here is a video that demonstrates how to do a complete ABC system flush.

What Scanner Can I Use to Diagnose Active Body Control Problems on a Mercedes-Benz?

If you’re experiencing problems with your Mercedes-Benz, a YOUCANIC full system diagnostic scanner can help you troubleshoot the issues. This advanced diagnostic tool can read and interpret the fault codes stored in your car’s computer system, providing detailed information about any problems with the engine, transmission, brakes, or other critical systems.

The YOUCANIC scanner can also perform diagnostic tests on various systems, including the ABS, airbag, and steering systems, to help pinpoint the root cause of any issues. With this information, you can make more informed decisions about repairs and maintenance, saving time and money on costly repairs.

Frequently Asked Questions

Which Mercedes has an ABC suspension?

Chassis equipped with ABC suspension include 215, 216, 220, and 221. The models with ABC suspension will have CODE 487 Active Body Control.

What is Mercedes ABC’s Recommended flush interval?

We would recommend flushing the Mercedes ABC system approximately every 50,000 miles.

Use a vacuum pump to suck out the old fluid?

Yes, but using a vacuum pump will not change all of the ABC fluid. You will replace only about 30% of the fluid by sucking out the old fluid and filling it with new ABC fluid. Make sure to do this with the engine off.