Code
U1600
ALFA ROMEO
U — Network/User
Immobilizer
Views:
UK: 6
EN: 6
RU: 8
AI status
Completed
Completed
100%
Causes
- Weak or disconnected battery supply
- Blown fuse related to immobilizer or body control module
- Damaged or corroded connectors/wiring to the immobilizer antenna coil, immobilizer ECU or gateway module
- Faulty immobilizer control module (ECU)
- Key transponder failure or damaged key
- Faulty/passive entry/antenna coil / reader unit
Symptoms
- Engine crank inhibited or no-crank condition (starter disabled)
- Immobilizer warning lamp or security indicator illuminated on dash
- Unable to start the vehicle or intermittent starting failures
- Other modules reporting U-codes or loss of communication faults
- Remote unlock/start functions not operating
- Key recognition errors or ‘‘KEY NOT RECOGNIZED’’ messages
What to check
- Scan all control modules and record all stored U- and B- codes and freeze frame data
- Check battery voltage (with load) and battery terminals; ensure charging system healthy
- Inspect related fuses and relays for immobilizer, body control and gateway modules
- Visually inspect connectors and wiring at immobilizer ECU, antenna/reader coil, key reader, gateway and instrument cluster for corrosion, damage or poor seating
- Check for aftermarket alarms/wiring tied into CAN or power circuits and remove/disable for test
- Attempt communication with the immobilizer module using a dealer-level scanner; note communication status
Signal parameters
- Vehicle battery nominal voltage ~12 V (should be stable during tests)
- CAN bus idle voltage (individual CAN_H/CAN_L ~2.5 V each; differential signaling present)
- CAN/LIN message presence when scanning (module should respond to poll)
- Antenna coil/transponder frequency/response (immobilizer reader energizes transponder at ~125 kHz; transponder should reply)
- Resistance/continuity of antenna coil wiring per factory spec (varies by model)
Diagnostic algorithm
- Read and record all stored codes from all modules; erase codes and reproduce to confirm persistent U1600.
- Verify battery voltage and charging system; ensure stable supply (12.4–12.8 V at rest). Recharge or replace battery if low.
- Check fuses and relays for immobilizer, BCM, gateway and instrument cluster; replace as needed.
- Visually inspect and gently wiggle connectors and wiring for the immobilizer ECU, antenna/reader coil near ignition, and gateway while monitoring for communication restoration.
- Attempt communication with immobilizer module using manufacturer diagnostic tool; note if module is present and responsive.
- Test spare/known-good key; if key not recognized, test antenna coil and transponder presence (using diagnostic tool or scope if available).
- Measure CAN bus voltages and continuity; check for shorts to ground or battery and verify proper termination resistances. Repair wiring faults.
- If communication is intermittent or module not responding, try swapping or re-seating gateway/BCM connectors where applicable (follow safety/programming procedures).
- If wiring and power are good but immobilizer ECU still not communicating, consult dealer procedures for immobilizer module firmware reflash or replacement and required key reprogramming. Preserve original module until confirmed necessary.
- After repair, clear codes and perform full system verification including start attempts and module communication checks.
Likely causes
- Low battery voltage or poor battery connections preventing module wake-up
- Damaged connector or wiring at immobilizer antenna coil or immobilizer ECU
- Failed immobilizer ECU or corrupted firmware
- Faulty key/transponder or worn key battery (if remote key required)
- CAN bus open, short, or termination fault affecting immobilizer messages
Fault status
Status
Lost or invalid communication with the immobilizer (anti-theft) control module; immobilizer messages not present on vehicle network.
Repair difficulty: Hard
Diagnostic time: 1.5-3.0 hours
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Code
U1600
FIAT
U — Network/User
Immobilizer
Views:
UK: 7
EN: 7
RU: 8
AI status
Completed
Completed
100%
Causes
- Weak or disconnected battery supply
- Blown fuse related to immobilizer or body control module
- Damaged or corroded connectors/wiring to the immobilizer antenna coil, immobilizer ECU or gateway module
- Faulty immobilizer control module (ECU)
- Key transponder failure or damaged key
- Faulty/passive entry/antenna coil / reader unit
Symptoms
- Engine crank inhibited or no-crank condition (starter disabled)
- Immobilizer warning lamp or security indicator illuminated on dash
- Unable to start the vehicle or intermittent starting failures
- Other modules reporting U-codes or loss of communication faults
- Remote unlock/start functions not operating
- Key recognition errors or ‘‘KEY NOT RECOGNIZED’’ messages
What to check
- Scan all control modules and record all stored U- and B- codes and freeze frame data
- Check battery voltage (with load) and battery terminals; ensure charging system healthy
- Inspect related fuses and relays for immobilizer, body control and gateway modules
- Visually inspect connectors and wiring at immobilizer ECU, antenna/reader coil, key reader, gateway and instrument cluster for corrosion, damage or poor seating
- Check for aftermarket alarms/wiring tied into CAN or power circuits and remove/disable for test
- Attempt communication with the immobilizer module using a dealer-level scanner; note communication status
Signal parameters
- Vehicle battery nominal voltage ~12 V (should be stable during tests)
- CAN bus idle voltage (individual CAN_H/CAN_L ~2.5 V each; differential signaling present)
- CAN/LIN message presence when scanning (module should respond to poll)
- Antenna coil/transponder frequency/response (immobilizer reader energizes transponder at ~125 kHz; transponder should reply)
- Resistance/continuity of antenna coil wiring per factory spec (varies by model)
Diagnostic algorithm
- Read and record all stored codes from all modules; erase codes and reproduce to confirm persistent U1600.
- Verify battery voltage and charging system; ensure stable supply (12.4–12.8 V at rest). Recharge or replace battery if low.
- Check fuses and relays for immobilizer, BCM, gateway and instrument cluster; replace as needed.
- Visually inspect and gently wiggle connectors and wiring for the immobilizer ECU, antenna/reader coil near ignition, and gateway while monitoring for communication restoration.
- Attempt communication with immobilizer module using manufacturer diagnostic tool; note if module is present and responsive.
- Test spare/known-good key; if key not recognized, test antenna coil and transponder presence (using diagnostic tool or scope if available).
- Measure CAN bus voltages and continuity; check for shorts to ground or battery and verify proper termination resistances. Repair wiring faults.
- If communication is intermittent or module not responding, try swapping or re-seating gateway/BCM connectors where applicable (follow safety/programming procedures).
- If wiring and power are good but immobilizer ECU still not communicating, consult dealer procedures for immobilizer module firmware reflash or replacement and required key reprogramming. Preserve original module until confirmed necessary.
- After repair, clear codes and perform full system verification including start attempts and module communication checks.
Likely causes
- Low battery voltage or poor battery connections preventing module wake-up
- Damaged connector or wiring at immobilizer antenna coil or immobilizer ECU
- Failed immobilizer ECU or corrupted firmware
- Faulty key/transponder or worn key battery (if remote key required)
- CAN bus open, short, or termination fault affecting immobilizer messages
Fault status
Status
Lost or invalid communication with the immobilizer (anti-theft) control module; immobilizer messages not present on vehicle network.
Repair difficulty: Hard
Diagnostic time: 1.5-3.0 hours
Similar codes
Your experience will help others
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Code
U1600
Generic
U — Network/User
Lost Communication with Instrument Panel Cluster (IPC) Control Module
Views:
UK: 5
EN: 7
RU: 7
AI status
Completed
Completed
100%
Causes
- Weak or disconnected battery supply
- Blown fuse related to immobilizer or body control module
- Damaged or corroded connectors/wiring to the immobilizer antenna coil, immobilizer ECU or gateway module
- Faulty immobilizer control module (ECU)
- Key transponder failure or damaged key
- Faulty/passive entry/antenna coil / reader unit
Symptoms
- Engine crank inhibited or no-crank condition (starter disabled)
- Immobilizer warning lamp or security indicator illuminated on dash
- Unable to start the vehicle or intermittent starting failures
- Other modules reporting U-codes or loss of communication faults
- Remote unlock/start functions not operating
- Key recognition errors or ‘‘KEY NOT RECOGNIZED’’ messages
What to check
- Scan all control modules and record all stored U- and B- codes and freeze frame data
- Check battery voltage (with load) and battery terminals; ensure charging system healthy
- Inspect related fuses and relays for immobilizer, body control and gateway modules
- Visually inspect connectors and wiring at immobilizer ECU, antenna/reader coil, key reader, gateway and instrument cluster for corrosion, damage or poor seating
- Check for aftermarket alarms/wiring tied into CAN or power circuits and remove/disable for test
- Attempt communication with the immobilizer module using a dealer-level scanner; note communication status
Signal parameters
- Vehicle battery nominal voltage ~12 V (should be stable during tests)
- CAN bus idle voltage (individual CAN_H/CAN_L ~2.5 V each; differential signaling present)
- CAN/LIN message presence when scanning (module should respond to poll)
- Antenna coil/transponder frequency/response (immobilizer reader energizes transponder at ~125 kHz; transponder should reply)
- Resistance/continuity of antenna coil wiring per factory spec (varies by model)
Diagnostic algorithm
- Read and record all stored codes from all modules; erase codes and reproduce to confirm persistent U1600.
- Verify battery voltage and charging system; ensure stable supply (12.4–12.8 V at rest). Recharge or replace battery if low.
- Check fuses and relays for immobilizer, BCM, gateway and instrument cluster; replace as needed.
- Visually inspect and gently wiggle connectors and wiring for the immobilizer ECU, antenna/reader coil near ignition, and gateway while monitoring for communication restoration.
- Attempt communication with immobilizer module using manufacturer diagnostic tool; note if module is present and responsive.
- Test spare/known-good key; if key not recognized, test antenna coil and transponder presence (using diagnostic tool or scope if available).
- Measure CAN bus voltages and continuity; check for shorts to ground or battery and verify proper termination resistances. Repair wiring faults.
- If communication is intermittent or module not responding, try swapping or re-seating gateway/BCM connectors where applicable (follow safety/programming procedures).
- If wiring and power are good but immobilizer ECU still not communicating, consult dealer procedures for immobilizer module firmware reflash or replacement and required key reprogramming. Preserve original module until confirmed necessary.
- After repair, clear codes and perform full system verification including start attempts and module communication checks.
Likely causes
- Low battery voltage or poor battery connections preventing module wake-up
- Damaged connector or wiring at immobilizer antenna coil or immobilizer ECU
- Failed immobilizer ECU or corrupted firmware
- Faulty key/transponder or worn key battery (if remote key required)
- CAN bus open, short, or termination fault affecting immobilizer messages
Fault status
Status
Lost or invalid communication with the immobilizer (anti-theft) control module; immobilizer messages not present on vehicle network.
Repair difficulty: Hard
Diagnostic time: 1.5-3.0 hours
Similar codes
Workshop Manuals
Available brands with manuals
1
LAND ROVER 2
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop ManualOfficial workshop manual for the Land Rover Defender 300Tdi (from 1996 model year). Contains specifications, adjustment, fault diagnosis and step-by-step repair and overhaul procedures for engine, transmission, axles, suspension, brakes, electrical and body. Intended for dealer workshops and trained technicians.
199,00 UAH
Land Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop ManualWorkshop Manual Supplement and Body Repair Manual for the Land Rover Defender. Includes general specifications, maintenance schedules, tuning data and step‑by‑step repair procedures for engine, transmission, suspension, brakes, electrical and body repairs. Covers Defender models from 1999 and 2002 model years.
199,00 UAH
Your experience will help others
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