P0B1B

Code

LAND ROVER P — Powertrain

hybrid/electric vehicle battery - Voltage - C Sense - Low circuit

Brand: LAND ROVER

Type: P — Powertrain

Views: UK: 15 EN: 21 RU: 16

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Causes

Open or shorted C-sense wiring (open to supply, short to ground)
Loose, corroded or damaged connector at the battery module, BMS or junction connector
Faulty C-sense sensor or voltage divider module on the HV battery module
Failed BMS / battery monitoring electronics
Water intrusion or contamination in harness/connectors
Blown fuse or failed low-voltage supply/reference for the sense circuit

Symptoms

HV system warning lamp(s) and hybrid/EV system message on the dash
Reduced power or limited drive (limp mode)
Charging disabled or reduced charging capability
Loss of regenerative braking or altered regen behavior
Possible inability to start or engage electric drive
DTC present and may persist after restart

What to check

Follow all manufacturer high-voltage (HV) safety procedures and isolate the HV system before any physical checks
Read full DTC list, freeze frame and diagnostic data with a compatible scan tool
Inspect visible C-sense wiring, connectors and junctions for damage, corrosion, moisture or loose pins
Check related fuses, relays and low-voltage supplies that feed the BMS sensing circuits
Verify reference supply voltage (e.g., 5 V reference) and ground integrity at the BMS connector
Measure the C-sense signal voltage at the BMS and at the battery module harness (with HV system isolated) and compare to expected values

Signal parameters

Expected analog sense voltage: typically within a mid-range value relative to the BMS reference (manufacturer-specific).
Low circuit condition: signal near 0 V or below the lower threshold (e.g., < ~0.2 V) indicating a low/grounded/open condition.
Open-circuit: no measurable voltage or erratic/no data reported for the C-sense channel.
High/erratic readings: may indicate short to supply or internal module fault (contrasts with low condition).
Note: exact thresholds and scaling are manufacturer-specific; consult wiring diagrams and service data for precise values.

Diagnostic algorithm

Safety and preparation: Read all stored codes and freeze-frame data. Isolate HV system and follow Land Rover HV safety procedures before touching the pack or HV wiring.
Visual inspection: With HV isolated, inspect C-sense wiring, connectors, junction boxes and the battery module for damage, corrosion, signs of water ingress, or previous repair work.
Connector checks: Disconnect and inspect mating faces/pins for corrosion, bent pins, or back-pinning. Clean and repair per manufacturer guidance.
Supply & ground verification: With appropriate low-voltage isolation and procedures, verify the BMS reference supply (often a 5 V feed) and ground are present and within spec at the BMS connector.
Signal measurement: Measure the C-sense voltage at the BMS connector and at the module end (with HV isolated). Compare to expected values from service data. A reading near 0 V indicates a low circuit.
Continuity/resistance: Check continuity and resistance of the C-sense conductor between BMS and module. Look for shorts to ground or to supply.
Wiggle / stress test: While monitoring live data with a scan tool, gently manipulate harnesses and connectors to reproduce intermittent faults.
Isolate module vs harness: If wiring and connectors test OK, suspect the module's sense circuitry or BMS input channel. If possible, swap or bench-test the sensing module or use a known-good harness/connector to confirm.
Repair or replace: Repair damaged wiring or connectors per OEM procedures. Replace faulty sensor/module/BMS only after confirming the component is the fault.
Clear codes and verify: Clear DTCs, re-enable HV system per procedures, perform functional test/drive and monitor live data. Confirm no reoccurrence of the code and proper battery behavior.
If unresolved: Consult manufacturer technical bulletins, wiring diagrams, and advanced diagnostics (module-level test equipment or module bench testing). Consider replacement of the HV battery pack or BMS only after thorough verification.

Likely causes

Damaged or disconnected C-sense wiring or connector at the HV battery module
Corroded connector pin causing high resistance and low measured voltage
Failed cell-sense board or voltage sensing circuit within the battery pack
Faulty BMS input channel for the C-sense circuit
Low reference supply (e.g., 5 V) or blown fuse feeding the sense circuit

Fault status

⚠️ Status

Hybrid/EV battery voltage C-sense low circuit detected. The battery management system has detected an abnormally low signal on the C-sense input. This can cause reduced propulsion, disabled charging or a warning message. Inspect the HV battery wiring, connectors and BMS; do not drive long distances until checked by a qualified technician.

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 2-6 hours

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P0B1B — hybrid/electric vehicle battery - Voltage - C Sense - Low circuit