B0121Fluid Reservoir Level Sensor F
- Generic OBD-II code · Body
- How the car detects it
- B0121 closes the row with level sensor F. Small local reservoirs are one reason a vehicle might carry six level sensors: Ford's application DE102018109892A1 describes a camera washer with its own container close to the lens, fitted with a buoyant level sensor that signals when the fluid has fallen to a set low point and the container needs topping up. How the result reaches the driver is a separate design question; Mannesmann VDO's patent US6588270B1 even moved the washer level display next to the fuel filler neck so that it is noticed while refuelling. No manufacturer publishes which reservoir F stands for or documents B0121. Driving is not affected, but the washer it watches may run dry unnoticed.
- What you may notice
- Missing or permanent refill message for the affected reservoir
- Washer served by this reservoir runs dry without warning
- Likely causes
- LikelyFloat of sensor F stuck by deposits or ice
- PossibleWiring to the small reservoir chafed or connector corroded
- RareLevel sensor F defective
- Repair
- Medium · Often possible to do yourself.Typical cost: €20 – €200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.