- Garden
- Pressure washers
BOOST function is not shown
Kärcher BOOST function is not shown on pressure washer: heat
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
On Kärcher K 5 and K 7 Smart Control pressure washers, when the BOOST function is not shown on the display and cannot be started via the KÄRCHER Home & Garden app, the device is overheated: check that water inlet temperature does not exceed 40 °C (K 5) or 60 °C (K 7) and lower it.
Safety first
Stop and check this first
- Risk of scalding from hot water: when disconnecting the garden supply hose or high-pressure hose after operation, hot water can leak out of the connections; close the water tap first, press the gun lever for 30 seconds to release system pressure, switch off at 0/OFF and pull the mains plug.
- Never modify or bypass the motor circuit breaker or other safety devices, and switch off the device if it does not build up pressure within 2 minutes to prevent dry-running damage to the pump.
Safe checks you can perform
- Check and reduce the water supply temperature (max 40 °C on K 5, 60 °C on K 7)
- Wait until the LCD display stops flashing after a 30-second BOOST run and hold +
- Switch off at 0/OFF and allow 1 hour to cool down if the motor circuit breaker triggered
Leave these tasks to a qualified professional
- Do not attempt this professional task: Thermal and motor circuit breaker inspection by authorised Kärcher Customer Service
- Do not attempt this professional task: Repair of electrical and motor components by authorised customer service only
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.
Thermal and motor circuit breaker inspection by authorised Kärcher Customer Service
What they doWhen overheating that blocks the BOOST function or trips the motor circuit breaker occurs repeatedly despite water inlet temperature below 40 °C (K 5) or 60 °C (K 7), authorised Customer Service inspects the device.
They must show youa 30-second BOOST activation on the LCD display and via the KÄRCHER Home & Garden app.
In writingthe cause of the overheating found, any original parts replaced, and warranty coverage.
Repair of electrical and motor components by authorised customer service only
What they doIf a material or manufacturing defect in the motor cooling path or electrical components on type 1.317-xxx or 1.324-xxx causes recurring overheating, authorised Customer Service carries out the repair with original spare parts.
They must show youfault-free operation without motor circuit breaker trips and normal BOOST response via the + button.
In writingthe original Kärcher spare part numbers installed and the electrical test confirmation.
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.
Check and reduce the water supply temperature (max 40 °C on K 5, 60 °C on K 7)
- Who:
- you, checking the water supply tap and garden hose.
- How:
- check the water supply temperature entering the cleaner against chapter Technical data: maximum input temperature is 40 °C for K 5 Smart Control Flex / K 5 Premium Smart Control Flex and 60 °C for K 7 Smart Control / K 7 Premium Smart Control. Reduce the water supply temperature (for instance by flushing sun-warmed water from the garden hose) to give the motor more cooling.
- Result that matters:
- cooler inlet water within the permissible temperature limit cooling the motor.
- If reducing the water supply temperature restores BOOST on the LCD and in the app:
- the device was overheated.
- If water is already cool and you just used a 30-second BOOST burst:
- check whether the display is still flashing.
- Evidence to keep:
- a note of the water supply temperature and a screenshot from the KÄRCHER Home & Garden app.
Evidence: Kärcher K 7 Smart Control and K 7 Premium Smart Control Operating Instructions (59688190) · Kärcher K 5 Smart Control and K 5 Premium Smart Control Operating Instructions (59797770)
Wait until the LCD display stops flashing after a 30-second BOOST run and hold +
- Who:
- you, operating the Smart Control high-pressure gun.
- How:
- note that the BOOST function can be activated for 30 seconds regardless of the pressure level set and that after BOOST expires the device works at the previously set pressure level. Wait until the LCD display stops flashing, then hold down the + button on the high-pressure gun until BOOST is highlighted on the LCD display.
- Result that matters:
- BOOST highlighting on the gun LCD display for a 30-second high-pressure burst.
- If BOOST highlights once the display stops flashing:
- the gun was in its normal post-BOOST cooldown.
- If the cleaner has shut off completely because the motor is overloaded:
- follow the 1-hour motor circuit breaker cool-down.
- Evidence to keep:
- a photo of the gun LCD once flashing stops and when holding down the + button.
Evidence: Kärcher K 7 Smart Control and K 7 Premium Smart Control Operating Instructions (59688190) · Kärcher K 5 Smart Control and K 5 Premium Smart Control Operating Instructions (59797770)
Switch off at 0/OFF and allow 1 hour to cool down if the motor circuit breaker triggered
- Who:
- you, no tools needed.
- How:
- if the motor is overloaded and the motor circuit breaker has triggered, switch off the device at 0/OFF, lock the lever of the high-pressure gun, and allow the device to cool down for 1 hour; also always switch off at 0/OFF during work breaks longer than 5 minutes. After 1 hour, switch the device on at I/ON and resume operation.
- Result that matters:
- the motor circuit breaker resetting and the cooled cleaner running with BOOST available.
- If the cleaner starts and BOOST works after cooling:
- keep inlet water cool and switch off during breaks over 5 minutes.
- If the overheating lockout recurs despite cool inlet water:
- have the device checked by authorised Customer Service.
- Evidence to keep:
- a record of the 1-hour cooling period and whether the fault recurs.
Evidence: Kärcher K 7 Smart Control and K 7 Premium Smart Control Operating Instructions (59688190) · Kärcher K 5 Smart Control and K 5 Premium Smart Control Operating Instructions (59797770)
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
- Kärcher
- Product type
- Pressure washers
Known code variants
- BOOST cannot be started via the KÄRCHER Home & Garden app
- BOOST function is not shown
- BOOST function is not shown on the display
- BOOST no se puede iniciar a través de la aplicación KÄRCHER Home & Garden
- Función BOOST parpadea Karcher
- Karcher BOOST display flashing
- Karcher Smart Control device is overheated
- Karcher Smart Control equipo sobrecalentado
- La función BOOST no se muestra en la pantalla
What it means
Operating instructions 59688190 (K 7 Smart Control and K 7 Premium Smart Control) and 59797770 (K 5 Smart Control and K 5 Premium Smart Control) list BOOST function is not shown on the display and cannot be started via the KÄRCHER Home & Garden app. The documented cause is that the device is overheated, and the remedy is to check the water supply temperature (maximum 40 °C on K 5 Smart Control Flex and 60 °C on K 7 Smart Control) and reduce it to give the motor more cooling; also, after a 30-second BOOST run, BOOST is available again once the display stops flashing. Other models differ, and this state alone never proves a part is faulty.
Warnings and stop conditions
- Highsource verified
Risk of scalding from hot water: when disconnecting the garden supply hose or high-pressure hose after operation, hot water can leak out of the connections; close the water tap first, press the gun lever for 30 seconds to release system pressure, switch off at 0/OFF and pull the mains plug.
Evidence: Kärcher K 7 Smart Control and K 7 Premium Smart Control Operating Instructions (59688190) · Kärcher K 5 Smart Control and K 5 Premium Smart Control Operating Instructions (59797770)
- Mediumsource verified
Never modify or bypass the motor circuit breaker or other safety devices, and switch off the device if it does not build up pressure within 2 minutes to prevent dry-running damage to the pump.
Evidence: Kärcher K 7 Smart Control and K 7 Premium Smart Control Operating Instructions (59688190) · Kärcher K 5 Smart Control and K 5 Premium Smart Control Operating Instructions (59797770)
Symptoms and causes
Probable causes · in order
- The device is overheated due to high water supply temperatureCommon
Kärcher's troubleshooting guide states that the BOOST function is not shown on the display and cannot be started via the KÄRCHER Home & Garden app when the device is overheated, requiring you to check and reduce the water supply temperature.
Evidence: Kärcher K 7 Smart Control and K 7 Premium Smart Control Operating Instructions (59688190) · Kärcher K 5 Smart Control and K 5 Premium Smart Control Operating Instructions (59797770)
- LCD display still flashing immediately after a 30-second BOOST activationPossible
Under Activating the BOOST function, Kärcher notes that BOOST runs for 30 seconds when holding down the + button and only becomes available again as soon as the display stops flashing.
Evidence: Kärcher K 7 Smart Control and K 7 Premium Smart Control Operating Instructions (59688190) · Kärcher K 5 Smart Control and K 5 Premium Smart Control Operating Instructions (59797770)
- Motor overloaded and motor circuit breaker triggered by high power drawLess common
If overheating coincides with an overloaded motor and excessive power consumption, the motor circuit breaker shuts off the device and requires switching off at 0/OFF and cooling down for 1 hour.
Evidence: Kärcher K 7 Smart Control and K 7 Premium Smart Control Operating Instructions (59688190) · Kärcher K 5 Smart Control and K 5 Premium Smart Control Operating Instructions (59797770)
Virtual technician
Does BOOST function is not shown 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
- 1
Kärcher K 7 Smart Control and K 7 Premium Smart Control Operating Instructions (59688190)
Alfred Kärcher SE & Co. KG · 2020 · official_doc
- 2
Kärcher K 7 Smart Control y K 7 Premium Smart Control Manual de instrucciones (59688190)
Alfred Kärcher SE & Co. KG · 2020 · official_doc
- 3
Kärcher K 5 Smart Control and K 5 Premium Smart Control Operating Instructions (59797770)
Alfred Kärcher SE & Co. KG · 2025 · official_doc
- 4
Kärcher K 5 Smart Control y K 5 Premium Smart Control Manual de instrucciones (59797770)
Alfred Kärcher SE & Co. KG · 2025 · official_doc
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