Code
U1118
CITROEN
U — Network/User
Fault absence of communication with the built-in systems interface (BSI): No signal
Views:
UK: 0
EN: 2
RU: 1
AI status
Completed
Completed
100%
Causes
- Blown fuse or low vehicle battery voltage
- Loose, corroded or damaged connector at BSI
- Broken, shorted or high-resistance CAN or LIN wiring/harness
- Failed BSI module or other gateway/module causing bus silence
- Missing or failed network termination resistor(s)
- Software/firmware fault or incompatible module update
Symptoms
- No communication with BSI in a diagnostic scanner
- Multiple modules report communication errors or U-codes
- Loss of central functions (lighting, wipers, locks, instrument cluster anomalies)
- Intermittent or permanent vehicle no-start or limp behaviours tied to body control functions
What to check
- Verify battery state of charge and battery terminal connections are clean and tight
- Check fuses and relays related to BSI power and ignition circuits
- Use a diagnostic tool to attempt to communicate with the BSI and read freeze frame/related codes
- Visually inspect BSI connector and harness for corrosion, pin damage, water ingress or recent repair splice points
- Check for other modules reporting bus errors — note patterns (CAN High/Low nets affected)
- Measure CAN/LIN physical layer signals at the BSI connector with multimeter/oscilloscope
Signal parameters
- Typical CAN idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V)
- Common CAN bus baud rates: 500 kbps (many systems); some networks use 250 kbps or 125 kbps — verify vehicle-specific rate
- Expected termination: two 120 Ohm resistors in parallel → ≈60 Ohms between CAN_H and CAN_L across the entire bus
Diagnostic algorithm
- Confirm battery >12.4 V and stable. Recharge or replace battery if low.
- Check and replace any blown fuses/relays powering the BSI. Confirm ignition power and ground circuits at the BSI connector with key on/off.
- Connect manufacturer-grade scanner. Attempt to communicate with BSI and record all codes from BSI and gateway modules.
- Visually inspect BSI connector and harness for corrosion, bent pins, moisture, or rodent damage. Repair connector or pins as needed.
- With ignition on, measure CAN_H and CAN_L voltages at the BSI connector. If voltages absent or stuck, isolate physical layer faults.
- Measure termination resistance between CAN_H and CAN_L with ignition off; expect ~60 ohms. If open or shorted, trace wiring for damage or remove sections to locate the fault.
- If bus voltages present but no logical communication, use an oscilloscope to view CAN waveform for noise, stuck dominant bits, or malformed frames.
- Disconnect nonessential modules one at a time (or harness sections) to see if a downstream module is holding the bus low/high. Recheck communication after each isolation.
- If wiring and other modules test good, try BSI power-cycle and perform any recommended software/firmware updates or reprogramming per manufacturer procedure.
- If BSI remains non-communicative after wiring and power verified, consider replacing BSI or sending for repair/reprogramming. Always program/initialize replacement module per Citroën procedures.
Likely causes
- Battery voltage low or intermittent causing BSI to be inactive
- Poor ground or power supply to BSI
- Damaged CAN/LIN wires at common splice points or after recent repairs
- Faulty BSI connector pins (bent/corroded) or internal BSI power/communication failure
- Other module holding the bus dominant or bus shorted to supply/ground
Fault status
Status
No signal — absence of communication with the BSI (Built-in Systems Interface).
Repair difficulty: Medium
Diagnostic time: 1.5-4 hours
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Code
U1118
DS
U — Network/User
Fault absence of communication with the built-in systems interface (BSI): No signal
Views:
UK: 0
EN: 0
RU: 0
AI status
Completed
Completed
100%
Causes
- Blown fuse or low vehicle battery voltage
- Loose, corroded or damaged connector at BSI
- Broken, shorted or high-resistance CAN or LIN wiring/harness
- Failed BSI module or other gateway/module causing bus silence
- Missing or failed network termination resistor(s)
- Software/firmware fault or incompatible module update
Symptoms
- No communication with BSI in a diagnostic scanner
- Multiple modules report communication errors or U-codes
- Loss of central functions (lighting, wipers, locks, instrument cluster anomalies)
- Intermittent or permanent vehicle no-start or limp behaviours tied to body control functions
What to check
- Verify battery state of charge and battery terminal connections are clean and tight
- Check fuses and relays related to BSI power and ignition circuits
- Use a diagnostic tool to attempt to communicate with the BSI and read freeze frame/related codes
- Visually inspect BSI connector and harness for corrosion, pin damage, water ingress or recent repair splice points
- Check for other modules reporting bus errors — note patterns (CAN High/Low nets affected)
- Measure CAN/LIN physical layer signals at the BSI connector with multimeter/oscilloscope
Signal parameters
- Typical CAN idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V)
- Common CAN bus baud rates: 500 kbps (many systems); some networks use 250 kbps or 125 kbps — verify vehicle-specific rate
- Expected termination: two 120 Ohm resistors in parallel → ≈60 Ohms between CAN_H and CAN_L across the entire bus
Diagnostic algorithm
- Confirm battery >12.4 V and stable. Recharge or replace battery if low.
- Check and replace any blown fuses/relays powering the BSI. Confirm ignition power and ground circuits at the BSI connector with key on/off.
- Connect manufacturer-grade scanner. Attempt to communicate with BSI and record all codes from BSI and gateway modules.
- Visually inspect BSI connector and harness for corrosion, bent pins, moisture, or rodent damage. Repair connector or pins as needed.
- With ignition on, measure CAN_H and CAN_L voltages at the BSI connector. If voltages absent or stuck, isolate physical layer faults.
- Measure termination resistance between CAN_H and CAN_L with ignition off; expect ~60 ohms. If open or shorted, trace wiring for damage or remove sections to locate the fault.
- If bus voltages present but no logical communication, use an oscilloscope to view CAN waveform for noise, stuck dominant bits, or malformed frames.
- Disconnect nonessential modules one at a time (or harness sections) to see if a downstream module is holding the bus low/high. Recheck communication after each isolation.
- If wiring and other modules test good, try BSI power-cycle and perform any recommended software/firmware updates or reprogramming per manufacturer procedure.
- If BSI remains non-communicative after wiring and power verified, consider replacing BSI or sending for repair/reprogramming. Always program/initialize replacement module per Citroën procedures.
Likely causes
- Battery voltage low or intermittent causing BSI to be inactive
- Poor ground or power supply to BSI
- Damaged CAN/LIN wires at common splice points or after recent repairs
- Faulty BSI connector pins (bent/corroded) or internal BSI power/communication failure
- Other module holding the bus dominant or bus shorted to supply/ground
Fault status
Status
No signal — absence of communication with the BSI (Built-in Systems Interface).
Repair difficulty: Medium
Diagnostic time: 1.5-4 hours
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Code
U1118
Other
U — Network/User
SCP (J1850) Invalid or Missing Data for Primary Id
Views:
UK: 18
EN: 22
RU: 25
AI status
Completed
Completed
100%
Causes
- Blown fuse or low vehicle battery voltage
- Loose, corroded or damaged connector at BSI
- Broken, shorted or high-resistance CAN or LIN wiring/harness
- Failed BSI module or other gateway/module causing bus silence
- Missing or failed network termination resistor(s)
- Software/firmware fault or incompatible module update
Symptoms
- No communication with BSI in a diagnostic scanner
- Multiple modules report communication errors or U-codes
- Loss of central functions (lighting, wipers, locks, instrument cluster anomalies)
- Intermittent or permanent vehicle no-start or limp behaviours tied to body control functions
What to check
- Verify battery state of charge and battery terminal connections are clean and tight
- Check fuses and relays related to BSI power and ignition circuits
- Use a diagnostic tool to attempt to communicate with the BSI and read freeze frame/related codes
- Visually inspect BSI connector and harness for corrosion, pin damage, water ingress or recent repair splice points
- Check for other modules reporting bus errors — note patterns (CAN High/Low nets affected)
- Measure CAN/LIN physical layer signals at the BSI connector with multimeter/oscilloscope
Signal parameters
- Typical CAN idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V)
- Common CAN bus baud rates: 500 kbps (many systems); some networks use 250 kbps or 125 kbps — verify vehicle-specific rate
- Expected termination: two 120 Ohm resistors in parallel → ≈60 Ohms between CAN_H and CAN_L across the entire bus
Diagnostic algorithm
- Confirm battery >12.4 V and stable. Recharge or replace battery if low.
- Check and replace any blown fuses/relays powering the BSI. Confirm ignition power and ground circuits at the BSI connector with key on/off.
- Connect manufacturer-grade scanner. Attempt to communicate with BSI and record all codes from BSI and gateway modules.
- Visually inspect BSI connector and harness for corrosion, bent pins, moisture, or rodent damage. Repair connector or pins as needed.
- With ignition on, measure CAN_H and CAN_L voltages at the BSI connector. If voltages absent or stuck, isolate physical layer faults.
- Measure termination resistance between CAN_H and CAN_L with ignition off; expect ~60 ohms. If open or shorted, trace wiring for damage or remove sections to locate the fault.
- If bus voltages present but no logical communication, use an oscilloscope to view CAN waveform for noise, stuck dominant bits, or malformed frames.
- Disconnect nonessential modules one at a time (or harness sections) to see if a downstream module is holding the bus low/high. Recheck communication after each isolation.
- If wiring and other modules test good, try BSI power-cycle and perform any recommended software/firmware updates or reprogramming per manufacturer procedure.
- If BSI remains non-communicative after wiring and power verified, consider replacing BSI or sending for repair/reprogramming. Always program/initialize replacement module per Citroën procedures.
Likely causes
- Battery voltage low or intermittent causing BSI to be inactive
- Poor ground or power supply to BSI
- Damaged CAN/LIN wires at common splice points or after recent repairs
- Faulty BSI connector pins (bent/corroded) or internal BSI power/communication failure
- Other module holding the bus dominant or bus shorted to supply/ground
Fault status
Status
No signal — absence of communication with the BSI (Built-in Systems Interface).
Repair difficulty: Medium
Diagnostic time: 1.5-4 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
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0
Send to email
Code
U1118
PEUGEOT
U — Network/User
Fault absence of communication with the built-in systems interface (BSI): No signal
Views:
UK: 0
EN: 1
RU: 0
AI status
Completed
Completed
100%
Causes
- Blown fuse or low vehicle battery voltage
- Loose, corroded or damaged connector at BSI
- Broken, shorted or high-resistance CAN or LIN wiring/harness
- Failed BSI module or other gateway/module causing bus silence
- Missing or failed network termination resistor(s)
- Software/firmware fault or incompatible module update
Symptoms
- No communication with BSI in a diagnostic scanner
- Multiple modules report communication errors or U-codes
- Loss of central functions (lighting, wipers, locks, instrument cluster anomalies)
- Intermittent or permanent vehicle no-start or limp behaviours tied to body control functions
What to check
- Verify battery state of charge and battery terminal connections are clean and tight
- Check fuses and relays related to BSI power and ignition circuits
- Use a diagnostic tool to attempt to communicate with the BSI and read freeze frame/related codes
- Visually inspect BSI connector and harness for corrosion, pin damage, water ingress or recent repair splice points
- Check for other modules reporting bus errors — note patterns (CAN High/Low nets affected)
- Measure CAN/LIN physical layer signals at the BSI connector with multimeter/oscilloscope
Signal parameters
- Typical CAN idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V)
- Common CAN bus baud rates: 500 kbps (many systems); some networks use 250 kbps or 125 kbps — verify vehicle-specific rate
- Expected termination: two 120 Ohm resistors in parallel → ≈60 Ohms between CAN_H and CAN_L across the entire bus
Diagnostic algorithm
- Confirm battery >12.4 V and stable. Recharge or replace battery if low.
- Check and replace any blown fuses/relays powering the BSI. Confirm ignition power and ground circuits at the BSI connector with key on/off.
- Connect manufacturer-grade scanner. Attempt to communicate with BSI and record all codes from BSI and gateway modules.
- Visually inspect BSI connector and harness for corrosion, bent pins, moisture, or rodent damage. Repair connector or pins as needed.
- With ignition on, measure CAN_H and CAN_L voltages at the BSI connector. If voltages absent or stuck, isolate physical layer faults.
- Measure termination resistance between CAN_H and CAN_L with ignition off; expect ~60 ohms. If open or shorted, trace wiring for damage or remove sections to locate the fault.
- If bus voltages present but no logical communication, use an oscilloscope to view CAN waveform for noise, stuck dominant bits, or malformed frames.
- Disconnect nonessential modules one at a time (or harness sections) to see if a downstream module is holding the bus low/high. Recheck communication after each isolation.
- If wiring and other modules test good, try BSI power-cycle and perform any recommended software/firmware updates or reprogramming per manufacturer procedure.
- If BSI remains non-communicative after wiring and power verified, consider replacing BSI or sending for repair/reprogramming. Always program/initialize replacement module per Citroën procedures.
Likely causes
- Battery voltage low or intermittent causing BSI to be inactive
- Poor ground or power supply to BSI
- Damaged CAN/LIN wires at common splice points or after recent repairs
- Faulty BSI connector pins (bent/corroded) or internal BSI power/communication failure
- Other module holding the bus dominant or bus shorted to supply/ground
Fault status
Status
No signal — absence of communication with the BSI (Built-in Systems Interface).
Repair difficulty: Medium
Diagnostic time: 1.5-4 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
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👍 Like
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0
Send to email