U2118

Code

CITROEN U — Network/User

Vehicle speed wake-up status word reception anomaly fault by the BSI: Data invalid

Brand: CITROEN

Type: U — Network/User

Views: UK: 27 EN: 51 RU: 39

AI status

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Page language: EN

Faulty sender module (instrument cluster, gateway or ABS/ESP module) transmitting the wake-up/status message
Damaged CAN/LIN wiring or poor connector/ground at the BSI or sender module
CAN bus interference, short to battery/ground or bus off condition
Low or unstable battery voltage or poor power/ground to BSI or sender module
Software/firmware mismatch, corrupted module software or configuration
Intermittent module or connector corrosion causing corrupted frames

Communication-related warning messages or lamp illumination
Speedometer/odometer or instrument cluster incorrect or inoperative
Automatic wake/sleep functions not working (central locking, remote wake, timers)
Cruise control, start/stop or other speed-dependent functions may be disabled
Intermittent or permanent loss of related vehicle features
Possible battery drain if modules fail to enter sleep

Read all stored and pending U- and P-codes from all modules; note occurrence frequency and freeze frame data
Check battery voltage and charging system; ensure good battery state (12.4–12.8 V resting) and stable voltage during cranking
Inspect BSI and relevant module connectors for corrosion, bent pins, water ingress, or poor mating
Visually inspect CAN/LIN wiring for chafing, damage or repairs between BSI and speed-sending modules (ABS, cluster, gateway)
Use a diagnostic tool to list modules present on the bus and check for any module 'not present' or communication errors
Monitor live data for vehicle speed and wake-up status words from the sending module(s) while observing for valid values

Message: vehicle speed / wake-up status word transmitted on vehicle CAN (manufacturer-specific message)
Expected: properly formatted CAN frames with correct ID, DLC and checksum if used; consistent message frequency during wake
Typical values: vehicle speed field should be within physically possible range (0–vehicle max) and status bits indicating wake/sleep state valid
Electrical: CAN bus idle voltages CAN_H ≈ 2.5–3.5 V, CAN_L ≈ 0.5–2.5 V; differential when active ~2.5 V
Timing: message refresh rate depends on manufacturer — watch for missing frames or irregular intervals

Confirm and document the fault: read and save full diagnostic report, note occurrence count and any accompanying codes.
Clear code and perform a road/wake test to see if U2118 returns. Observe live data while driving or during wake sequence.
Check battery state and ensure stable supply to BSI and sender modules; repair or replace battery if voltage is poor.
Visually inspect and secure all related connectors (BSI, instrument cluster, ABS/ESP, gateway). Clean and re-seat where necessary.
Use a diagnostic tool to query the sending module(s) for vehicle speed and wake status. If the sender reports invalid data, focus on that module.
Monitor the CAN bus with a scan tool or oscilloscope: verify presence of the expected message ID, correct DLC and consistent timing. Look for corrupted frames or bus errors.
If a particular module is not transmitting or is sending corrupt data, perform module-specific tests (wheel speed sensors for ABS, cluster self-tests). Repair or replace faulty sensors or module as indicated.
Check/repair wiring harness faults between the sender and BSI (continuity, resistance, shorts to battery/ground).
If wiring and sensors are good, consider BSI firmware update or reprogramming per manufacturer service information.
If fault persists after logical checks and software updates, consider replacing the defective module (BSI or sender) and re-test.
Note: follow manufacturer service documentation and use appropriate tools for CAN network isolation and module programming.

Poor connector/ground at BSI or at the module that provides vehicle speed (wheel speed/ABS or instrument cluster)
CAN wiring open/short between sender module and BSI
Faulty ABS/ESP or instrument cluster sending invalid speed/wake data
BSI software fault or BSI internal failure
Temporary bus communication error after battery disconnect or jump-start

⚠️ Status

BSI - Vehicle speed wake-up status word received is invalid (communication/data error).

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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