B0300

Code

LAND ROVER B — Body

Network management expulsion

Brand: LAND ROVER

Type: B — Body

Views: UK: 14 EN: 25 RU: 14

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Page language: EN

Causes

Faulty or non-responsive control module
Intermittent or open/short on vehicle CAN/LIN network wiring or connectors
Missing or incorrect network termination resistors
Low or unstable battery/ground voltage during bus wake/sleep events
Corroded/water-damaged connectors or damaged module power/ground
Software/configuration mismatch or failed module initialization after update

Symptoms

Warning or lamp illumination for affected systems
Loss of one or more vehicle functions controlled by the expelled module
Related communication DTCs present (U0xxx codes)
Intermittent operation of modules that wake/sleep with ignition
Vehicle may enter limp or reduced functionality mode for affected systems

What to check

Scan all modules for U- and B-codes and note which module reports B0300
Check freeze-frame/fault occurrence data and time stamps
Inspect wiring harness and connectors for the affected module(s) for corrosion, damage, or loose pins
Verify battery voltage and ground integrity (at-rest and during crank)
Check CAN/LIN bus physical layer with a multimeter: continuity and resistance across CAN_H–CAN_L (~60 Ω total)
Use an oscilloscope or diagnostic tool to view CAN_H/CAN_L signals during wake/sleep and normal operation

Signal parameters

CAN bus idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (recessive)
CAN bus dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2 V)
Typical termination resistance: ≈ 60 Ω across CAN_H and CAN_L (two 120 Ω in parallel)
Network Management (NM) message periodicity and timeouts (manufacturer-specific; check service data)
Battery voltage range expected during diagnostics: nominal 12.0–14.6 V

Diagnostic algorithm

Record freeze-frame and full DTC list from all modules; save for reference
Identify which module reports B0300 and confirm other modules show related communication errors (U-codes)
Visually inspect connectors, pins and wiring for the affected module(s); repair any corrosion or damage
Measure battery voltage and primary ground at the module and at chassis — repair poor grounds
Measure CAN_H and CAN_L voltages with key on and engine running; compare to expected values
Measure termination resistance across CAN_H–CAN_L at multiple points in the harness (~60 Ω). If open or incorrect, locate and repair missing/failed terminators
Use an oscilloscope to capture CAN signals during attempted module wake; look for lack of NM messages, dominant-only states, or excessive noise/bit errors
If physical layer checks OK, check module programming/firmware levels and reflash or reconfigure according to manufacturer procedures
Disconnect suspected aftermarket devices or non-OEM modules and re-test
If module is confirmed non-responsive after wiring and power verified, follow publisher repair procedure — replace module only after confirming fault
Clear codes and perform a road or use-cycle test to ensure the module joins the network and no B0300 returns

Likely causes

Failed or sleeping control module (internal fault)
Open/shorted CAN_H or CAN_L wiring or poor connector contact
Missing/incorrect termination (not ~60 Ω across CAN_H–CAN_L)
Low battery voltage during module wake sequence
Module software or calibration mismatch following repair or update

Fault status

⚠️ Status

Module has been expelled or lost from the vehicle network management system. The module is not participating on the bus and communication with the rest of the vehicle is impaired.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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