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Home / DTC / B122A — seat cushion right fan speed sensor

B122A — seat cushion right fan speed sensor

Detailed page for trouble code B122A.

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Code

B122A

LAND ROVER B — Body

seat cushion right fan speed sensor

Brand: LAND ROVER
Type: B — Body
Views: UK: 1 EN: 6 RU: 3
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Page language: EN

Causes

  • Open or short in the right seat cushion fan speed sensor wiring
  • Corroded, loose or damaged connector at the sensor or seat module
  • Failed seat cushion fan speed sensor (internal fault)
  • Faulty seat control module or body control module driving the fan
  • Blower motor or fan assembly mechanical/electrical fault
  • Water ingress or contamination in the seat cushion area

Symptoms

  • Right seat ventilation (cooling) blower not working or stuck at one speed
  • Reduced or no air flow from right seat cushion vents
  • Seat ventilation system error message or warning on the instrument cluster/infotainment
  • Intermittent operation of the right seat fan (works when position changed or when harness moved)
  • Possible increased cabin/seat discomfort for occupant on affected side

What to check

  • Retrieve freeze-frame and live data with a diagnostic scan tool; note reported fan speed/sensor values
  • Visually inspect the right seat cushion area for signs of water, debris or damage
  • Inspect connector locking tabs and pins for corrosion, bent pins, or poor contact
  • Wiggle test harness/connector while observing live data to check for intermittent faults
  • Check for related codes in the seat/BCM/climate control modules
  • Verify fuse(s) and ground(s related to seat ventilation and seat module

Signal parameters

  • Supply: typically switched 12 V and/or a 5 V reference from the seat module (verify with vehicle documentation)
  • Signal: sensor output should change with fan speed selection (either variable voltage or PWM duty cycle reported by scan tool)
  • Ground: low resistance to chassis ground when measured at the connector
  • Expected behavior: signal toggles smoothly across speeds, no open-circuit or constant out-of-range values

Diagnostic algorithm

  1. Use a capable scan tool to read the DTC, live data and any related codes; record freeze-frame data and current fan speed/sensor values.
  2. Attempt to reproduce the fault by operating seat ventilation across all speeds and observe live data for the right cushion fan.
  3. Visually inspect the seat cushion, fan assembly and harness routing for signs of damage, chafing, water ingress or contamination.
  4. With ignition on, backprobe the sensor connector and verify supply voltage, ground continuity and sensor output while changing fan speeds. Compare behavior to expected (output should vary with speed).
  5. Perform a wiggle test on the harness and connector while monitoring live data to find intermittent faults.
  6. Check continuity between the sensor connector and the seat/BCM pin; check for shorts to battery or ground.
  7. If wiring and connectors are good, swap or bench-test the seat cushion fan speed sensor (if serviceable) or replace the fan/sensor assembly per manufacturer procedure and retest.
  8. If sensor and wiring test good, investigate seat control module / body control module outputs and software (consult service info for reflash or module tests).
  9. After repair, clear codes and confirm normal operation across all speeds and that the DTC does not return.

Likely causes

  • Connector corrosion or pin damage at the seat cushion fan sensor
  • Broken/abraded wiring in the harness from the seat to the module (common at seat belt area or seat base)
  • Failed sensor element inside the cushion fan assembly
  • Poor ground or supply to the seat module

Fault status

⚠️ Status
Right seat cushion fan speed sensor signal fault detected (open/short/implausible). Seat ventilation for right cushion may be inoperative or operate incorrectly. Diagnostic trouble code stored in body/seat module.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-1.5 hours

Similar codes

B122B B1220 B128A B129A B12C0
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