These instructions apply to the Mercedes A-Class Mk4 (W177) 2018-Present.
For other models, please choose your vehicle here.
When the spanner or an “ASSYST PLUS” service message appears on your Mercedes A-Class Mk4 (W177, 2018–present), the service interval has elapsed. It is a maintenance reminder, not a fault. Mercedes uses its ASSYST PLUS menu, reached through the instrument cluster, to reset it. It’s a few more steps than most cars, but no tools are needed. Do the service first, then follow the sequence carefully.
What ASSYST PLUS Is Telling You
ASSYST PLUS is the A-Class’s active service system. Rather than counting down a fixed distance alone, it tracks how the car is used — distance, time, and driving conditions — and works out when the next service is due. When that point is reached it shows the spanner symbol and a service message, often with a countdown of remaining days or distance in the run-up. It records the actual service carried out and the oil used, which is why the reset asks you to confirm those details rather than just zeroing a number. Crucially, this is a maintenance prompt: it is separate from the red and amber warning lamps that indicate a genuine fault, and resetting it will not clear a real fault.
Reset Only After the Service
ASSYST PLUS records the actual service that’s been done, so only confirm it once the oil and filter are genuinely changed. Confirming the service before the work is finished stores incorrect data and shortens the accuracy of the next interval calculation. Park on level ground, apply the parking brake, and have the car stationary before you begin.
Before You Begin
You only need the ignition on with the engine off, and no tools. The whole reset is done from the steering-wheel buttons and the instrument cluster. Because ASSYST PLUS hides its service menu behind a “Workshop” section that you open with a two-button hold, it helps to read the steps through once first so the timing feels familiar — the hidden menu only appears if the second button is pressed within about a second of the first and both are held.
How to Reset the A-Class W177 Service (ASSYST PLUS)
- Close the bonnet, all doors and the boot. Turn the ignition to position 2 (on, engine off).
- Using the steering-wheel buttons, press the right-hand display button until the standard (Trip) display shows, and scroll to the ‘Trip’ menu.
- To open the hidden menu: press and hold the right-hand display button, and within 1 second also press the left-hand button; keep both pressed for about 5 seconds.
- The ‘Workshop’ menu appears (Vehicle data / Dynamometer test / ASSYST PLUS). Select ‘ASSYST PLUS’.
- Select ‘Full service’, then ‘Confirm service’.
- Select the oil specification you used, then ‘Yes’. A “cannot be undone” warning appears; confirm until the display shows ‘Confirmation’.
If You Make a Mistake
The confirmation can’t be reversed, so take care to select the correct service and oil spec. If you only want to top up the remaining distance rather than confirm a full service, exit without confirming.
If the Reset Doesn’t Work
If the Workshop menu never appears or the service message stays after you finish, the usual causes are timing and menu position:
- The hidden menu won’t open: you must be on the Trip display first, then hold the right button and add the left button within about a second, keeping both down for roughly five seconds. If it doesn’t appear, release and try again.
- A door or the bonnet is open: close everything up — the system may not let you into the service menu otherwise.
- The message returns at next start-up: you probably didn’t reach ‘Confirmation’. Repeat carefully through Full service → Confirm service and confirm past the “cannot be undone” warning.
- Don’t start the engine mid-reset: keep the ignition in position 2 throughout; starting up drops you out of the menu.
After the Reset
Once the display shows ‘Confirmation’, ASSYST PLUS logs the service you selected and calculates the next interval from the oil spec you entered. The spanner symbol and service message clear, and the countdown resets to the newly calculated period. Nothing else on the car is altered.
How Often You’ll Need This
Confirm the service in ASSYST PLUS after every completed service. Because the system works the interval out from how the car is driven and the oil used, there isn’t a single fixed mileage that applies to every A-Class — follow the schedule in your owner’s handbook and let the system count down to the next due date. Each time the service message returns, have the work done and then confirm it here.
Frequently Asked Questions
What is ASSYST PLUS?
It’s Mercedes’ active service system — it tracks the actual service work and oil used, not just mileage. You confirm the completed service through its menu.
Do I need a diagnostic tool?
No — the reset is done from the steering-wheel buttons and the cluster menu.
Why does it ask for the oil specification?
ASSYST PLUS adjusts the next interval to the oil quality used, so it asks you to confirm the spec.
Why won’t the Workshop menu appear?
It only opens if you press the left-hand button within about a second of holding the right-hand button, and keep both held for around five seconds from the Trip display. Make sure the bonnet, doors and boot are closed, then try the two-button hold again.
The service message is still there — why?
You may not have reached ‘Confirmation’. Repeat carefully through Full service → Confirm service.
If a warning light appeared with the service message, look it up on autodtcs.com. After battery work, see our A-Class W177 battery guide.
Independent guide — not affiliated with Mercedes. Always follow your official service manual and safety precautions. Read our full disclaimer.