B1D71

Code

LAND ROVER B — Body

High frequency phase lock loop

Brand: LAND ROVER

Type: B — Body

Views: UK: 10 EN: 22 RU: 10

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Page language: EN

Causes

Intermittent or failed power supply to the module (low battery, blown fuse, corroded connector)
Poor or intermittent ground connection at the affected module
Damaged/contaminated connectors or wiring to antenna, transceiver or HF circuits
Failed internal PLL component or associated oscillator/crystal in the module
Software/firmware error or corruption in the controlling module
External radio frequency interference preventing lock

Symptoms

Malfunction or reduced performance of the subsystem using the PLL (example: degraded radio reception, nonfunctional radar/ADAS sensor, keyless entry / immobilizer issues, poor telematics HF link)
Related warning lamp(s) or message on infotainment/driver information display
Stored B1D71 code and possibly associated HF‑related codes
Intermittent operation that may vary with temperature or vehicle movement

What to check

Retrieve freeze frame and full fault list with a capable dealer-level or OEM diagnostic tool and note occurrence conditions
Check battery voltage and condition; test module power and ground pins for correct, stable voltages
Visually inspect module connectors, antenna connectors and wiring harness for corrosion, damage or moisture
Check fuses and relays that feed the affected module
Scan for related codes (other B or U codes) that may point to wiring or CAN bus issues
If the module has an external antenna or RF front-end, inspect and test that component (continuity, VSWR where applicable)

Signal parameters

Module supply voltage (nominal 12 V; acceptable operating range per vehicle spec)
Ground resistance (should be low;
Reference clock / oscillator frequency expected by the module (module-specific; check OEM data)
PLL lock status bit(s) reported over module diagnostics (LOCK/UNLOCK)
CAN/LIN message traffic: module alive messages and HF status codes
RF input amplitude and SNR at antenna/feed (manufacturer test values)

Diagnostic algorithm

Record all stored and pending codes, freeze frame data and symptom details before clearing codes
Perform a basic service check: fully charge battery or use battery support, then recheck the code with ignition cycles
Visually inspect and secure all harness connectors, antenna connectors and module grounds; repair any damage or corrosion
Measure module supply and ground at the connector with engine off and cranking; compare to spec
If accessible, check antenna continuity and feedline for short/open. Where applicable measure RF input level and VSWR per OEM procedure
Perform a software/firmware check and update/reflash module with latest OEM calibration if available
If wiring and power/ground are correct and the code persists, consider swapping with a known-good identical module (if available) or replace the module per OEM guidance
After repair or replacement, clear codes and perform functional tests for the affected subsystem. Monitor for recurrence over multiple ignition cycles and road/test conditions

Likely causes

Connector corrosion or water ingress at module or antenna
Module internal hardware failure (oscillator, PLL IC)
Power/ground fault to the module
Outdated or corrupt software requiring reflash

Fault status

⚠️ Status

High frequency phase‑lock loop fault detected in module — PLL not achieving/maintaining lock. Module reports HF PLL error; related HF function may be degraded or inoperative.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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