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Home / DTC / B1B38 — Sensor front left external

B1B38 — Sensor front left external

Detailed page for trouble code B1B38.

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B1B38

LAND ROVER B — Body

Sensor front left external

Brand: LAND ROVER
Type: B — Body
AI status
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Page language: EN

Causes

  • Contaminated, damaged or misaligned front-left external sensor (physical damage, water ingress, corrosion)
  • Broken, chafed or disconnected wiring/harness to the sensor
  • Corroded or loose connector or pin at sensor or module
  • Open or shorted sensor signal, power or ground circuit
  • Faulty sensor internal electronics
  • Intermittent connection due to movement or corrosion

Symptoms

  • DTC B1B38 stored in vehicle control module
  • Warning lamp or message on dash related to affected system (parking aid, exterior temperature, driver-assist sensor, depending on vehicle)
  • Loss or degradation of function tied to the front-left external sensor (reduced parking assist, blind spot, camera, or ambient measurement)
  • Intermittent or erratic sensor readings in live-data

What to check

  • Read DTCs and freeze-frame data with a Land Rover-capable scan tool and note related codes
  • Visually inspect the front-left external sensor for damage, contamination, or misalignment
  • Inspect the sensor connector for corrosion, bent pins, water, or foreign material
  • Follow the wiring harness from the sensor toward the module; look for chafe, pinches, heat damage, or broken wires
  • Check that related fuses/relays are present and correct
  • Use scan tool to observe live data from the sensor and check message frequency/values

Signal parameters

  • Supply voltage: typically 5 V or 12 V (verify vehicle-specific)
  • Signal voltage: often 0.0–5.0 V for analog sensors; may be PWM, frequency or digital message for ultrasonic/camera modules
  • CAN/LIN traffic: sensor reporting frequency commonly 5–100 Hz (varies by function)
  • Ultrasonic sensors: typical ultrasonic frequency ~40 kHz (acoustic), electrical drive pulses are millisecond-range
  • Temperature sensor (if applicable): NTC resistance ≈ 2–10 kΩ at 25°C (model dependent)
  • Expected sensor current draw: small (milliamps) for electronics; large deviations indicate fault

Diagnostic algorithm

  1. Connect OEM-level diagnostic tool and record all related DTCs, freeze-frame and live data for the front-left external sensor and related systems
  2. Visually inspect sensor and connector; disconnect connector and examine contacts for corrosion, bent pins or moisture
  3. Clean connector with appropriate electrical contact cleaner, dry fully, reconnect and check code status
  4. With ignition ON, measure supply voltage and ground at the sensor connector (verify correct reference voltage present)
  5. Measure sensor output signal while operating relevant function (or with applied stimulus) using multimeter/oscilloscope to confirm valid waveform/voltage
  6. Wiggle harness while observing live data/scan tool to try to reproduce fault — if reproduced, isolate wiring break or intermittent connector
  7. If wiring and connector are good, substitute a known-good sensor (or swap with right-side equivalent if identical) to confirm sensor failure
  8. Inspect and test CAN/LIN bus for voltage levels, termination and comms errors if sensor is networked; repair bus faults first
  9. If sensor replaced, follow manufacturer calibration/initialization procedures and clear codes; perform a function/road test to confirm repair
  10. If problem persists after sensor and wiring verified, consider module reflash, software update or module replacement per manufacturer guidance

Likely causes

  • Water ingress / corrosion at front-left sensor connector
  • Connector pins pushed out or bent during service
  • Frayed wiring where harness is routed over suspension or steering components
  • Failed sensor from road debris or impact
  • Fault in BCM / central module interpreting the sensor signal

Fault status

⚠️ Status
Manufacturer-specific fault: front-left external sensor signal invalid, missing or out of expected range. Affected system functionality may be reduced or disabled until fault is resolved.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

B1B37 B1B39 B1B3A B1B3B B1B3C
320

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