- Boilers
- Tankless gas water heater
F168
Vaillant F.168 on a gas water heater: water leak sensor fault
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
High
Quick answer
On the Vaillant turboMAG plus water heater, F.168 means the water leak sensor has found water inside the appliance or its circuit is faulty. Look for drips from outside, keep the casing closed and book a gas technician.
Safety first
Stop and check this first
- If you smell gas while the turboMAG plus shows F.168, do not operate switches, plugs, doorbells or phones, avoid any flame, open doors and windows if you can, close the meter or main gas valve and the appliance gas tap if possible, warn neighbours without ringing, leave the building, keep others out and call the emergency services and the gas supplier emergency line from outside.
Safe checks you can perform
- Look for water outside without opening it
- Take the heater out of use if it drips
- A single reset if no water is visible
- Collect the appliance details
Leave these tasks to a qualified professional
- Do not attempt this professional task: Locate and seal the internal leak
- Do not attempt this professional task: Test sensor, harness and board
- Do not attempt this professional task: Check tightness and operation
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.
Locate and seal the internal leak
What they doThe gas technician opens the appliance, finds where the water comes from in the circuit and seals it before restarting.
They must show youthe exact point where water was escaping.
In writingwhich part or joint was repaired.
Test sensor, harness and board
What they doWith no water present, they check the wiring harness and decide whether the water leak sensor or circuit board needs replacing.
They must show youthe test that clears or condemns the sensor.
In writingthe component replaced and why.
Check tightness and operation
What they doAfterwards they verify operation and tightness of the product and confirm the safety devices respond.
They must show youthe heater running without F.168.
In writingthe tightness test result.
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.
Look for water outside without opening it
Check beneath the turboMAG plus and along its water connections for drops, stains or a puddle. Do not remove the casing or touch the plug if water is near it. Note where the water appears so you can tell the technician handling F.168.
Evidence: Vaillant turboMAG plus MAG ..5/1-5 RT, instrucciones de funcionamiento 0020261985_00
Take the heater out of use if it drips
- If water is escaping, follow the temporary shutdown in the user manual:
- disconnect power only if the plug is dry, close the gas shut-off tap and close the cold water valve. That way F.168 waits for the technician with no more water going in.
Evidence: Vaillant turboMAG plus MAG ..5/1-5 RT, instrucciones de funcionamiento 0020261985_00
A single reset if no water is visible
With no visible leak, the user manual allows you to open and close the hot tap several times, switch the appliance off and on and press the reset button when an error shows. Do it once; if F.168 returns, stop and book the visit.
Evidence: Vaillant turboMAG plus MAG ..5/1-5 RT, instrucciones de funcionamiento 0020261985_00
Collect the appliance details
Copy the model from the data plate on the left side of the casing, the time F.168 appeared and whether water was visible. That tells the technician exactly which turboMAG plus to inspect.
Evidence: Vaillant turboMAG plus MAG ..5/1-5 RT, instrucciones de funcionamiento 0020261985_00
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
- Boilers
- Brand
- Vaillant
- Product type
- Tankless gas water heater
Known code variants
- F.168
- turboMAG F.168
- turboMAG plus F168
- Vaillant F.168
What it means
The turboMAG plus contains a water level sensor. The installation manual explains that if a water pipe inside the appliance leaks and the level rises to that sensor, the heater stops and shows a fault message. The fault table gives F.168 four causes: water in the product, a defective water leak sensor, a defective circuit board and a break in the wiring harness. The code alone therefore does not prove a leak: the technician has to separate real water from a detection fault.
Warnings and stop conditions
- Criticaleditorial warning
If you smell gas while the turboMAG plus shows F.168, do not operate switches, plugs, doorbells or phones, avoid any flame, open doors and windows if you can, close the meter or main gas valve and the appliance gas tap if possible, warn neighbours without ringing, leave the building, keep others out and call the emergency services and the gas supplier emergency line from outside.
Evidence: Vaillant turboMAG plus MAG ..5/1-5 RT, instrucciones de funcionamiento 0020261985_00
Symptoms and causes
Probable causes · in order
- Water inside the heaterCommon
A leak from an internal water pipe can raise the level to the sensor; the manufacturer remedy is to shut off the water and seal the leak.
Evidence: Vaillant turboMAG plus MAG ..5/1-5 RT, instrucciones de instalación y mantenimiento 0020261986_00
- Faulty water leak sensorPossible
If there is no water inside the appliance, the sensor itself may have failed and the table calls for replacing it.
Evidence: Vaillant turboMAG plus MAG ..5/1-5 RT, instrucciones de instalación y mantenimiento 0020261986_00
- Wiring harness or circuit boardPossible
A break in the sensor wiring harness or a defective circuit board can also produce F.168 with no leak present.
Evidence: Vaillant turboMAG plus MAG ..5/1-5 RT, instrucciones de instalación y mantenimiento 0020261986_00
Virtual technician
Does F168 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
- 2
Vaillant turboMAG plus MAG ..5/1-5 RT, instrucciones de funcionamiento 0020261985_00
Vaillant · 2018 · manual
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