B1B12

Code

LAND ROVER B — Body

transponder 10 Key

Brand: LAND ROVER

Type: B — Body

Views: UK: 24 EN: 170 RU: 18

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Damaged or failed key transponder (transponder chip in key)
Faulty or damaged immobilizer antenna/coil (around the ignition barrel or key reader)
Intermittent or lost power/ground to the immobilizer or antenna module
Poor connector contacts or corroded wiring between antenna and immobilizer/BCM
Immobilizer or body control module (BCM) software or hardware fault
CAN or LIN bus communication error between immobilizer and vehicle modules

Symptoms

Engine cranks but will not start or starter disabled
Security/immobilizer warning lamp illuminated or flashing
Intermittent no-start condition dependent on which key is used
Key not recognised messages on instrument cluster or infotainment
No remote start / central locking anomalies (in some cases)

What to check

Confirm B1B12 stored in module and note freeze frame / occurrence count
Attempt to start vehicle with all available keys (spare key test)
Inspect key(s) physically for damage, worn transponder plastic, or water intrusion
Check fuses and supply/ground at immobilizer/antenna module
Visually inspect antenna ring and its connector for damage and corrosion
Scan for related codes (immobilizer, BCM, CAN/UART/LIN communication faults)

Signal parameters

Transponder antenna supply voltage (typically ~12V or vehicle accessory feed)
Antenna coil continuity/resistance (expected low ohms; compare to spec)
Transponder excitation frequency ~125 kHz and amplitude (diagnostic tool readings where available)
Immobilizer/BCM CAN messages indicating key ID and authentication status
Key ID presence/absence reported by diagnostic tool during a read or key learn

Diagnostic algorithm

Retrieve and record the full immobilizer/BCM fault log and any related codes.
Try a known-good spare key. If spare works reliably, suspect the original key transponder and replace or reprogram the key.
Inspect the key for physical damage or water intrusion. Replace key shell if transponder chip is loose/damaged.
Verify power and ground at the immobilizer and antenna module; check relevant fuses and relays.
Measure antenna coil resistance/continuity at its connector; compare to manufacturer spec. Replace antenna if open/shorted or out of spec.
Inspect wiring and connectors between the antenna and immobilizer/BCM for corrosion, bent pins, or intermittent connections; repair as needed.
Use a capable diagnostic tool to read key IDs from the immobilizer and attempt a key re-learn/re-program sequence per manufacturer procedure.
Check CAN/LIN communications for errors; repair network faults if immobilizer cannot communicate with BCM/ECM.
If electrical and key tests are good, consider immobilizer module or BCM fault — consult manufacturer bulletins and consider module reflash/replacement as last step.
After repairs, clear codes and perform functional verification with each vehicle key; confirm no recurrence and successful starts.

Likely causes

Worn or broken transponder chip in the key (most common)
Antenna coil open or short (physical damage)
Connector corrosion at antenna ring or immobilizer module
Blown fuse or missing supply to immobilizer/antenna module
Software/firmware glitch requiring reinitialisation or reprogramming

Fault status

⚠️ Status

Transponder (key) communication fault detected — immobilizer not recognising key. Vehicle may not start; key re-learn, antenna, wiring, or immobilizer module should be checked.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-2 hours

Similar codes

Repair manuals

Manual library for LAND ROVER

413

Browse 413 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

LAND ROVER

Your experience will help others

+100 karma for a short comment :)

Was this AI description helpful?

Your feedback helps improve AI descriptions.

👍 Like 0 👎 Dislike 0

Send to email