- Garden
- Cordless garden tools
3 LEDs flash red
STIHL RMA 443.3 3 LEDs flash red: lawn mower fault alert
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
High
Quick answer
On the STIHL RMA 443.3 cordless lawn mower (36 V STIHL AK battery system), 3 LEDs flash red on the battery when the mower does not start when switched on, indicating a fault in the lawn mower. Remove the battery, clean the compartment electrical contacts, refit the battery and switch the mower on.
Safety first
Stop and check this first
- Always remove the AK battery before cleaning the battery compartment or performing any work on the lawn mower, never spray the lawn mower with water, and never attempt to repair the mower yourself or bypass the locking button or control bar.
- If 3 LEDs still flash red after cleaning the electrical contacts in the battery compartment and refitting the battery, do not use the RMA 443.3 lawn mower and consult a STIHL specialist dealer.
Safe checks you can perform
- Remove the AK battery on a level surface
- Clean the battery compartment and electrical contacts with a paintbrush or soft brush
- Fit the AK battery until it clicks and switch the lawn mower on on level ground
Leave these tasks to a qualified professional
- Do not attempt this professional task: Lawn mower fault diagnosis and repair at a STIHL specialist dealer
- Do not attempt this professional task: Safety inspection of the control bar, locking button and blade by a STIHL dealer
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Lawn mower fault diagnosis and repair at a STIHL specialist dealer
What they doIf 3 LEDs still flash red after you remove the battery, clean the electrical contacts in the battery compartment with a paintbrush or soft brush and refit the battery, a STIHL specialist dealer inspects and repairs the RMA 443.3 lawn mower.
They must show youthe RMA 443.3 lawn mower starting normally via the locking button and control bar without 3 flashing red LEDs.
In writingthe fault diagnosed in the RMA 443.3 lawn mower, the genuine STIHL spare parts fitted and warranty coverage.
Safety inspection of the control bar, locking button and blade by a STIHL dealer
What they doWhile servicing the mower fault, the STIHL specialist dealer checks that the locking button, control bar, battery compartment contacts and mower blade operate safely without damage or modification.
They must show youproper operation of the locking button and control bar stopping the blade when released.
In writingthe safety inspection findings for the controls, battery compartment and blade assembly.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Remove the AK battery on a level surface
- Who:
- you, with the STIHL RMA 443.3 lawn mower parked on level ground.
- How:
- follow Section 9.2 of the manual: place the lawn mower on a level surface, open flap (1) by handle (2) and hold it, hold battery (3), press locking lever (4) and remove battery (3).
- Result that matters:
- the AK battery safely removed from the lawn mower before inspecting the compartment.
- If the battery was in spare compartment (2) or not clicked into active compartment (1):
- proceed to clean and seat it in compartment (1).
- If the battery was locked in compartment (1) and showed 3 flashing red LEDs:
- continue to the contact cleaning step.
- Evidence to keep:
- a short video clip showing 3 LEDs flashing red on the battery when switching the RMA 443.3 on.
Evidence: STIHL RMA 443.3 Cordless Lawn Mower Instruction Manual (0478-131-9669-B, English, Troubleshooting & AK Battery LEDs)
Clean the battery compartment and electrical contacts with a paintbrush or soft brush
- Who:
- you, with the lawn mower switched off, the battery removed and no water spray.
- How:
- following Section 16.2 of manual 0478-131-9669-B, remove any foreign bodies from the battery compartment, clean the battery compartment with a damp cloth, and clean the electrical contacts in the battery compartment with a paintbrush or a soft brush.
- Result that matters:
- a clean battery compartment and electrical contacts free of grass or dirt.
- If foreign matter or dirt was on the compartment contacts:
- proceed to refit the AK battery and test startup.
- If the compartment and contacts were already clean:
- still perform the refitting and level startup check.
- Evidence to keep:
- a clear photo of active battery compartment (1) and its cleaned electrical contacts.
Evidence: STIHL RMA 443.3 Cordless Lawn Mower Instruction Manual (0478-131-9669-B, English, Troubleshooting & AK Battery LEDs)
Fit the AK battery until it clicks and switch the lawn mower on on level ground
- Who:
- you, operating the mower within the recommended 0 °C to +40 °C temperature range.
- How:
- following Sections 9.1 and 10.1.1, push the AK battery into compartment (1) as far as it will go until it audibly clicks into place; with the mower on a level surface and not tilted, press and hold locking button (1) with your right hand and pull control bar (2) with your left hand fully toward handlebar (3).
- Result that matters:
- the RMA 443.3 motor starting smoothly without 3 LEDs flashing red.
- If the lawn mower starts and runs normally:
- dirty contacts or incomplete seating caused the alert.
- If 3 LEDs still flash red:
- do not use the lawn mower, remove the battery and consult a STIHL specialist dealer.
- Evidence to keep:
- a note of the RMA 443.3 serial number and the STIHL AK battery model used.
Evidence: STIHL RMA 443.3 Cordless Lawn Mower Instruction Manual (0478-131-9669-B, English, Troubleshooting & AK Battery LEDs)
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Garden
- Brand
- STIHL
- Product type
- Cordless garden tools
Known code variants
- 3 LED parpadean en rojo
- 3 LEDs flash red
- 3 LEDs flashing red
- El cortacésped presenta una anomalía STIHL
- If 3 LEDs still flash red
- Si 3 LED siguen parpadeando en rojo
- STIHL AK 3 luces rojas parpadeando
- STIHL AK 3 red LEDs flashing
- STIHL RMA 443.3 3 LED parpadean en rojo
- STIHL RMA 443.3 3 LEDs flashing red
- There is a fault in the lawn mower STIHL
What it means
STIHL instruction manual 0478-131-9669-B for the STIHL RMA 443.3 cordless lawn mower (36 V STIHL AK battery system) documents in Section 19.1 the troubleshooting row where the lawn mower does not start when switched on and 3 LEDs are flashing red on the battery: the cause is that there is a fault in the lawn mower. The remedy is to remove the battery, clean the electrical contacts in the battery compartment, fit the battery and switch the lawn mower on; if 3 LEDs still flash red, do not use the lawn mower and consult a STIHL specialist dealer. Other models may differ, and this light pattern alone never proves a part is permanently faulty.
Warnings and stop conditions
- Highsource verified
Always remove the AK battery before cleaning the battery compartment or performing any work on the lawn mower, never spray the lawn mower with water, and never attempt to repair the mower yourself or bypass the locking button or control bar.
Evidence: STIHL RMA 443.3 Cordless Lawn Mower Instruction Manual (0478-131-9669-B, English, Troubleshooting & AK Battery LEDs)
- Mediumsource verified
If 3 LEDs still flash red after cleaning the electrical contacts in the battery compartment and refitting the battery, do not use the RMA 443.3 lawn mower and consult a STIHL specialist dealer.
Evidence: STIHL RMA 443.3 Cordless Lawn Mower Instruction Manual (0478-131-9669-B, English, Troubleshooting & AK Battery LEDs)
Symptoms and causes
Probable causes · in order
- Dirty electrical contacts inside the RMA 443.3 battery compartmentCommon
Section 19.1 of STIHL manual 0478-131-9669-B instructs you to remove the battery and clean the electrical contacts in the battery compartment first when 3 LEDs flash red at startup.
Evidence: STIHL RMA 443.3 Cordless Lawn Mower Instruction Manual (0478-131-9669-B, English, Troubleshooting & AK Battery LEDs)
- Foreign bodies in the battery compartment or AK battery not locked into placePossible
Sections 9.1 and 16.2 of the RMA 443.3 manual require removing any foreign bodies from active battery compartment (1) and pushing the AK battery in as far as it will go until it clicks into place and is locked.
Evidence: STIHL RMA 443.3 Cordless Lawn Mower Instruction Manual (0478-131-9669-B, English, Troubleshooting & AK Battery LEDs)
- Persistent fault in the STIHL RMA 443.3 lawn mowerLess common
According to Section 19.1 of manual 0478-131-9669-B, if 3 LEDs still flash red after you clean the electrical contacts in the battery compartment and refit the battery, there is a fault in the lawn mower requiring a STIHL specialist dealer.
Evidence: STIHL RMA 443.3 Cordless Lawn Mower Instruction Manual (0478-131-9669-B, English, Troubleshooting & AK Battery LEDs)
Virtual technician
Does 3 LEDs flash red still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
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