These instructions apply to the Mercedes GLA Mk2 (H247) 2020-Present.
For other models, please choose your vehicle here.
When the wrench symbol and an “A” or “B” service message appears on your Mercedes-Benz GLA (H247, 2020–present), the ASSYST PLUS maintenance counter is due. You reset it from the instrument-cluster menu with the steering-wheel buttons — no workshop tool needed. Do the service first.
What the GLA Service Message Means
ASSYST PLUS is the GLA’s built-in service scheduler, and the wrench message is a maintenance reminder rather than a fault — nothing has failed when it appears. The system tracks the distance you cover, the time since the last service and how the car is driven (cold starts, short journeys, engine load and oil temperature), and from that works out when the oil and the next inspection fall due. As the interval approaches, the cluster first counts down the remaining distance or days, then displays the spanner with an “A” or “B” letter once it is reached.
Because the calculation blends distance and time, a GLA that covers few miles will still be called in on the calendar, while a higher-mileage car reaches the point sooner on distance. If the counter shows a minus figure, the service is simply overdue by that amount — it is not an error.
A and B Service — What’s the Difference
Mercedes alternates two service depths. Service A is the lighter visit, typically engine oil and filter plus a set of checks. Service B is the fuller visit and usually adds items such as the cabin filter and further inspections. ASSYST PLUS decides which letter is due and shows it for you, so you don’t have to work it out — you reset the counter after whichever one has been carried out. The precise list of work for each letter, and the mileage or time cap for your engine and market, are given in your owner’s handbook and service booklet; use those figures rather than assuming a number.
Before You Begin
Reset ASSYST PLUS after the service is finished — fresh oil in, filter changed, any B-service items done. Resetting first only restarts the clock on old oil and hides the reminder. Then:
- Park on level ground with the electronic park brake applied.
- Set the ignition on with the engine off for the reset — you don’t need to run the engine.
- No tools are needed; it’s all done with the steering-wheel touch controls and the cluster menu.
- Close the doors, bonnet and boot before you begin, or the workshop menu won’t arm.
How to Reset the GLA Service Indicator
- Close the bonnet, boot and all doors.
- Turn the ignition to position 2.
- On the steering-wheel touch controls, scroll to the ‘Trip’ menu.
- Press and hold the OK button; within 1 second, also press the phone/back button, and keep both held for about 5 seconds.
- The hidden ‘Workshop’ menu appears (VEHICLE DATA / DYNAMOMETER TEST / ASSYST PLUS).
- Select ‘ASSYST PLUS’ → ‘Full service’ and confirm the reset.
If It Doesn’t Reset
The two-button step on the H247 cluster is timing-sensitive, so most trouble is with getting into the Workshop menu rather than the reset itself. Work through these:
- The timing is tight — the second button must follow within about 1 second of the first, and both must stay held for roughly 5 seconds. If the Workshop menu doesn’t open, release and try again.
- A door, bonnet or boot is open — the menu won’t arm; close everything and retry.
- Wrong starting menu — you must be on the Trip display when you press and hold; start from the wrong screen and the shortcut won’t trigger.
- You didn’t confirm — step fully through ASSYST PLUS → Full service → confirm; backing out early saves nothing.
- Still stuck — switch the ignition off, wait a few seconds, switch back on and repeat the whole sequence.
After the Reset
When the reset confirms, the wrench symbol and the A/B message clear straight away and the ASSYST PLUS counter returns to a full interval, counting down again from the day you reset it. If the spanner clears but reappears soon after, the confirmation didn’t take — run the sequence again to the end.
How Often You’ll Need This
Reset ASSYST PLUS once after every completed service, and only then. The GLA uses a flexible, condition-based schedule rather than one fixed mileage, so the gap between services varies with how you drive. Let the car call for the next service rather than resetting to a number, and confirm the exact interval for your engine and region in the owner’s handbook.
Frequently Asked Questions
How do I reset the service light on a Mercedes GLA?
Via the cluster: open the Trip menu, hold OK then the second button together ~5 seconds to reach the Workshop menu, then ASSYST PLUS → Full service → confirm.
Do I need a Star or diagnostic tool?
No — ASSYST PLUS resets from the dashboard with the steering-wheel controls. A diagnostic tool is not needed for a routine service reset.
What do A and B service mean?
Mercedes alternates a smaller ‘A’ and larger ‘B’ service. ASSYST PLUS picks the right one; reset after whichever you’ve done.
The Workshop menu won’t open — what am I doing wrong?
Usually the button timing. Start on the Trip display, hold OK, add the second button within a second, and keep both held for about five seconds with all doors shut.
The message came back — why?
The reset wasn’t confirmed. Repeat and confirm to the end. A separate warning light, if lit, is a fault rather than the service timer.
Does resetting the counter service the car?
No. It only tells the car the maintenance has been done; it changes no oil and carries out no work. Do the physical service first, then reset.
If a warning light appeared with the service message, look it up on autodtcs.com. After battery work, see our GLA battery guide.
Independent guide — not affiliated with Mercedes. Always follow your official service manual and safety precautions. Read our full disclaimer.