Body, generic

B0120 Fluid Reservoir Level Sensor E

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

B0120 relates to level sensor E. Ford's application US20190265715A1 describes a container for sensor cleaning whose level sensor measures conductance at a fixed height: air gives a resistance above roughly 1000 ohms, the slightly conductive fluid one below it. Because the fluid moves with the car, the computer filters the signal with acceleration and yaw rate, then estimates the remaining volume from pump activity, and it suspects a leak if the level falls while no washing is requested, in which case the vehicle may be routed to a service centre. Ford's patent US10569746B2 puts such a container on the roof beside the lidar. Letter E is not tied publicly to any tank, and no manufacturer documents B0120. Without the signal, remaining fluid can only be guessed.

Likely causes

Electrodes fouled or fluid with unsuitable conductivity (e.g. plain distilled water)
Open or short in the sensor circuit
Leaking reservoir or hose making the level drop unexpectedly

Symptoms

  • Refill warning too early, too late or constantly on
  • Cleaning of exterior sensors may be restricted

Repair estimate

DifficultyMediumDIY possible
Parts and labour€20–250
Time0.3–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fluid reservoir level sensor esensor wiring

Related codes

B011CB011DB011EB011FB0121

References: patents.google.com, patents.google.com.