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Home / DTC / B0120 — Fluid Reservoir Level Sensor E

B0120 — Fluid Reservoir Level Sensor E

Detailed page for trouble code B0120.

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Code

B0120

Generic B — Body

Fluid Reservoir Level Sensor E

Brand: Generic
Type: B — Body
Views: UK: 21 EN: 31 RU: 22
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Page language: EN

Causes

  • Open or shorted wiring or connector to sensor
  • Corroded or loose connector pins
  • Failed level sensor or internal float/jaw mechanism
  • Low or contaminated fluid preventing proper float action
  • Blown fuse or poor ground for circuit
  • Intermittent connection from chafing or water ingress

Symptoms

  • Fluid level warning lamp or message for reservoir E illuminated
  • Incorrect or no level indication on dash/gauge
  • Intermittent or persistent fault lamp related to body/control module
  • Associated system limitations (depending on reservoir: reduced washer function, steering assist warnings, etc.)
  • Possible diagnostic trouble codes stored for related modules

What to check

  • Read freeze frame and full DTC list with a scan tool; note history and status
  • Visually inspect reservoir fluid level and condition
  • Inspect sensor connector for corrosion, bent pins, water, or contamination
  • Check harness for obvious damage, rubbing, or kinks between sensor and module
  • Verify applicable fuse(s) and main body/ECU power and ground
  • Backprobe sensor connector and observe live data or voltage with key on

Signal parameters

  • Typical sensor types: switch (open/closed) or resistive/voltage output (0–5 V).
  • Switch-style expected: continuity in one position (float up/down) and open in the other.
  • Voltage-style expected: approximately 0.0–5.0 V range — many systems show near 0 V when empty and near 4–5 V when full (manufacturer dependent).
  • Resistance-style: variable ohms based on float position; expect a stable change when float moves (compare to service data).
  • No communication or a stuck/unchanging value indicates an open or shorted circuit or failed sensor.

Diagnostic algorithm

  1. Connect a diagnostic scan tool. Read and record DTC B0120 and any related codes, freeze frame data, and live sensor values.
  2. Visually inspect the reservoir, sensor, harness, and connector for damage, corrosion, fluid intrusion, or disconnection. Top up fluid if very low and clean any contamination.
  3. Check related fuses and vehicle grounds. Repair any blown fuses and restore grounds before retesting.
  4. With ignition ON (engine off), backprobe the sensor connector. Measure reference voltage (if used), signal voltage, and ground continuity. Compare to expected ranges in Signal Parameters.
  5. If switch-type, check for continuity across the sensor terminals while moving the float. If no change, replace sensor or remove reservoir to inspect float mechanism.
  6. If voltage/resistance-type, measure resistance or voltage over float travel. If values do not change or are out of range, suspect sensor or wiring fault.
  7. Perform a wiring continuity and short-to-power/ground test between sensor connector and the control module pin. Repair broken wires or shorts.
  8. If wiring and connector are good but sensor still out of range, replace Fluid Reservoir Level Sensor E with OE or equivalent part and clear codes.
  9. After repair, clear DTCs and perform a road/operation test or cycle key to confirm the code does not return and live data behaves correctly.
  10. If the fault returns after correct sensor and wiring repair, consider module input diagnostics or consult manufacturer-specific service data.

Likely causes

  • Corroded/loose electrical connector at sensor
  • Damaged wiring harness (broken wire, short to ground/power)
  • Failed sensor (float stuck, internal electronics failed)
  • Reservoir fluid level extremely low or contaminated
  • Poor ground at reservoir or nearby body ground point

Fault status

⚠️ Status
Fault detected: Fluid Reservoir Level Sensor E circuit abnormal (open/short/intermittent/out-of-range). Inspection and repair of sensor, wiring, connector, fuses, and grounds recommended.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B0110 B0121 P0460 P0462 P0463
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