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Home / DTC / U1124 — Fault: absence of communication with the pneumatic suspension ECU: No signal

U1124 — Fault: absence of communication with the pneumatic suspension ECU: No signal

Detailed page for trouble code U1124.

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59brands
11,914generic
22,491specific
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Code

U1124

CITROEN U — Network/User

Fault: absence of communication with the pneumatic suspension ECU: No signal

Brand: CITROEN
Type: U — Network/User
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse or disabled power supply to the suspension ECU
  • Battery low voltage or poor battery connection
  • Open or shorted wiring to the ECU (power, ground or data lines)
  • Corroded, disconnected or damaged connector at the suspension ECU
  • CAN bus fault (open, short to ground/V+, missing termination)
  • Faulty pneumatic suspension ECU (internal failure)

Symptoms

  • Suspension warning lamp or message on dash
  • Automatic leveling or height adjustment inoperative
  • Compressor not running or no audible activity from suspension ECU
  • Vehicle ride height incorrect or sagging at one or more corners
  • Multiple network communication-related fault codes present
  • Inability of diagnostic scanner to communicate with the suspension ECU

What to check

  • Read all stored DTCs and freeze-frame data with a dedicated diagnostic tool
  • Verify battery voltage (key ON and engine off) — should be ~12–14.5 V
  • Check related fuses and relays for the suspension ECU circuit
  • Visually inspect connectors at the pneumatic suspension ECU for corrosion, bent pins or water ingress
  • Verify presence of other network modules and ability to communicate with them
  • Measure CAN H and CAN L voltages at the ECU connector and at a known-good location

Signal parameters

  • Battery supply to ECU: ~11–14.5 V (key ON); near battery voltage when awake
  • Ground:
  • CAN bus idle voltages (typical): CAN_H ~2.5–3.5 V, CAN_L ~1.5–2.5 V (approx. 2.5 V common-mode)
  • Dominant/active CAN differential voltage up to ~2 V
  • Termination resistance across CAN_H and CAN_L: ~60 ohm (two 120Ω in parallel)

Diagnostic algorithm

  1. Connect a diagnostic scanner and attempt to communicate with the pneumatic suspension ECU; record exact symptoms and stored codes.
  2. Check battery voltage and condition; charge or support battery if low and retry communication.
  3. Inspect and test fuses/relays feeding the suspension ECU; replace any blown fuses.
  4. Visually inspect ECU connector for corrosion, moisture, damaged pins or poor engagement; unplug, inspect and reconnect.
  5. With ignition ON, measure power and ground at the ECU connector pins; verify expected voltages and good chassis ground.
  6. Check CAN bus signals at the ECU connector with a multimeter or scope: verify idle voltages and differential behavior while communicating from a scanner or while other modules are active.
  7. Verify termination resistor across CAN_H and CAN_L (~60Ω). If termination incorrect, trace and repair short/open.
  8. If CAN voltages abnormal, isolate sections of the bus: disconnect the suspension ECU and check if other modules communicate; perform wiggle tests to locate intermittent wiring faults.
  9. If wiring and power/ground/CAN are good but no response, check for ECU wake-up signal from gateway or body control module; review manufacturer service information for wake-up procedure.
  10. If the ECU remains unresponsive, consider replacing or reflashing the ECU per manufacturer procedures. Before replacement, confirm with a known-good module or consult technical service bulletins.

Likely causes

  • Lost power or ground to the pneumatic suspension ECU (fuse, connector, wiring)
  • CAN bus break or short between ECU and gateway (open circuit or incorrect voltages)
  • Connector corrosion or poor contact at the suspension ECU
  • Module internal failure or module asleep and not responding to network wake-up

Fault status

⚠️ Status
Fault — no communication from pneumatic suspension ECU (no signal received).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0100 U0121 U0140 U0155 U0401
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Code

U1124

DS U — Network/User

Fault: absence of communication with the pneumatic suspension ECU: No signal

Brand: DS
Type: U — Network/User
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse or disabled power supply to the suspension ECU
  • Battery low voltage or poor battery connection
  • Open or shorted wiring to the ECU (power, ground or data lines)
  • Corroded, disconnected or damaged connector at the suspension ECU
  • CAN bus fault (open, short to ground/V+, missing termination)
  • Faulty pneumatic suspension ECU (internal failure)

Symptoms

  • Suspension warning lamp or message on dash
  • Automatic leveling or height adjustment inoperative
  • Compressor not running or no audible activity from suspension ECU
  • Vehicle ride height incorrect or sagging at one or more corners
  • Multiple network communication-related fault codes present
  • Inability of diagnostic scanner to communicate with the suspension ECU

What to check

  • Read all stored DTCs and freeze-frame data with a dedicated diagnostic tool
  • Verify battery voltage (key ON and engine off) — should be ~12–14.5 V
  • Check related fuses and relays for the suspension ECU circuit
  • Visually inspect connectors at the pneumatic suspension ECU for corrosion, bent pins or water ingress
  • Verify presence of other network modules and ability to communicate with them
  • Measure CAN H and CAN L voltages at the ECU connector and at a known-good location

Signal parameters

  • Battery supply to ECU: ~11–14.5 V (key ON); near battery voltage when awake
  • Ground:
  • CAN bus idle voltages (typical): CAN_H ~2.5–3.5 V, CAN_L ~1.5–2.5 V (approx. 2.5 V common-mode)
  • Dominant/active CAN differential voltage up to ~2 V
  • Termination resistance across CAN_H and CAN_L: ~60 ohm (two 120Ω in parallel)

Diagnostic algorithm

  1. Connect a diagnostic scanner and attempt to communicate with the pneumatic suspension ECU; record exact symptoms and stored codes.
  2. Check battery voltage and condition; charge or support battery if low and retry communication.
  3. Inspect and test fuses/relays feeding the suspension ECU; replace any blown fuses.
  4. Visually inspect ECU connector for corrosion, moisture, damaged pins or poor engagement; unplug, inspect and reconnect.
  5. With ignition ON, measure power and ground at the ECU connector pins; verify expected voltages and good chassis ground.
  6. Check CAN bus signals at the ECU connector with a multimeter or scope: verify idle voltages and differential behavior while communicating from a scanner or while other modules are active.
  7. Verify termination resistor across CAN_H and CAN_L (~60Ω). If termination incorrect, trace and repair short/open.
  8. If CAN voltages abnormal, isolate sections of the bus: disconnect the suspension ECU and check if other modules communicate; perform wiggle tests to locate intermittent wiring faults.
  9. If wiring and power/ground/CAN are good but no response, check for ECU wake-up signal from gateway or body control module; review manufacturer service information for wake-up procedure.
  10. If the ECU remains unresponsive, consider replacing or reflashing the ECU per manufacturer procedures. Before replacement, confirm with a known-good module or consult technical service bulletins.

Likely causes

  • Lost power or ground to the pneumatic suspension ECU (fuse, connector, wiring)
  • CAN bus break or short between ECU and gateway (open circuit or incorrect voltages)
  • Connector corrosion or poor contact at the suspension ECU
  • Module internal failure or module asleep and not responding to network wake-up

Fault status

⚠️ Status
Fault — no communication from pneumatic suspension ECU (no signal received).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0100 U0121 U0140 U0155 U0401
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Keep it short and practical. Up to 500 characters.
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Code

U1124

MITSUBISHI U — Network/User

SAS(CAN message)

Brand: MITSUBISHI
Type: U — Network/User
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse or disabled power supply to the suspension ECU
  • Battery low voltage or poor battery connection
  • Open or shorted wiring to the ECU (power, ground or data lines)
  • Corroded, disconnected or damaged connector at the suspension ECU
  • CAN bus fault (open, short to ground/V+, missing termination)
  • Faulty pneumatic suspension ECU (internal failure)

Symptoms

  • Suspension warning lamp or message on dash
  • Automatic leveling or height adjustment inoperative
  • Compressor not running or no audible activity from suspension ECU
  • Vehicle ride height incorrect or sagging at one or more corners
  • Multiple network communication-related fault codes present
  • Inability of diagnostic scanner to communicate with the suspension ECU

What to check

  • Read all stored DTCs and freeze-frame data with a dedicated diagnostic tool
  • Verify battery voltage (key ON and engine off) — should be ~12–14.5 V
  • Check related fuses and relays for the suspension ECU circuit
  • Visually inspect connectors at the pneumatic suspension ECU for corrosion, bent pins or water ingress
  • Verify presence of other network modules and ability to communicate with them
  • Measure CAN H and CAN L voltages at the ECU connector and at a known-good location

Signal parameters

  • Battery supply to ECU: ~11–14.5 V (key ON); near battery voltage when awake
  • Ground:
  • CAN bus idle voltages (typical): CAN_H ~2.5–3.5 V, CAN_L ~1.5–2.5 V (approx. 2.5 V common-mode)
  • Dominant/active CAN differential voltage up to ~2 V
  • Termination resistance across CAN_H and CAN_L: ~60 ohm (two 120Ω in parallel)

Diagnostic algorithm

  1. Connect a diagnostic scanner and attempt to communicate with the pneumatic suspension ECU; record exact symptoms and stored codes.
  2. Check battery voltage and condition; charge or support battery if low and retry communication.
  3. Inspect and test fuses/relays feeding the suspension ECU; replace any blown fuses.
  4. Visually inspect ECU connector for corrosion, moisture, damaged pins or poor engagement; unplug, inspect and reconnect.
  5. With ignition ON, measure power and ground at the ECU connector pins; verify expected voltages and good chassis ground.
  6. Check CAN bus signals at the ECU connector with a multimeter or scope: verify idle voltages and differential behavior while communicating from a scanner or while other modules are active.
  7. Verify termination resistor across CAN_H and CAN_L (~60Ω). If termination incorrect, trace and repair short/open.
  8. If CAN voltages abnormal, isolate sections of the bus: disconnect the suspension ECU and check if other modules communicate; perform wiggle tests to locate intermittent wiring faults.
  9. If wiring and power/ground/CAN are good but no response, check for ECU wake-up signal from gateway or body control module; review manufacturer service information for wake-up procedure.
  10. If the ECU remains unresponsive, consider replacing or reflashing the ECU per manufacturer procedures. Before replacement, confirm with a known-good module or consult technical service bulletins.

Likely causes

  • Lost power or ground to the pneumatic suspension ECU (fuse, connector, wiring)
  • CAN bus break or short between ECU and gateway (open circuit or incorrect voltages)
  • Connector corrosion or poor contact at the suspension ECU
  • Module internal failure or module asleep and not responding to network wake-up

Fault status

⚠️ Status
Fault — no communication from pneumatic suspension ECU (no signal received).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0100 U0121 U0140 U0155 U0401
406

Browse 406 MITSUBISHI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MITSUBISHI

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Code

U1124

Other U — Network/User

SCP (J1850) Invalid or Missing Data for Primary Id

Brand: Other
Type: U — Network/User
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse or disabled power supply to the suspension ECU
  • Battery low voltage or poor battery connection
  • Open or shorted wiring to the ECU (power, ground or data lines)
  • Corroded, disconnected or damaged connector at the suspension ECU
  • CAN bus fault (open, short to ground/V+, missing termination)
  • Faulty pneumatic suspension ECU (internal failure)

Symptoms

  • Suspension warning lamp or message on dash
  • Automatic leveling or height adjustment inoperative
  • Compressor not running or no audible activity from suspension ECU
  • Vehicle ride height incorrect or sagging at one or more corners
  • Multiple network communication-related fault codes present
  • Inability of diagnostic scanner to communicate with the suspension ECU

What to check

  • Read all stored DTCs and freeze-frame data with a dedicated diagnostic tool
  • Verify battery voltage (key ON and engine off) — should be ~12–14.5 V
  • Check related fuses and relays for the suspension ECU circuit
  • Visually inspect connectors at the pneumatic suspension ECU for corrosion, bent pins or water ingress
  • Verify presence of other network modules and ability to communicate with them
  • Measure CAN H and CAN L voltages at the ECU connector and at a known-good location

Signal parameters

  • Battery supply to ECU: ~11–14.5 V (key ON); near battery voltage when awake
  • Ground:
  • CAN bus idle voltages (typical): CAN_H ~2.5–3.5 V, CAN_L ~1.5–2.5 V (approx. 2.5 V common-mode)
  • Dominant/active CAN differential voltage up to ~2 V
  • Termination resistance across CAN_H and CAN_L: ~60 ohm (two 120Ω in parallel)

Diagnostic algorithm

  1. Connect a diagnostic scanner and attempt to communicate with the pneumatic suspension ECU; record exact symptoms and stored codes.
  2. Check battery voltage and condition; charge or support battery if low and retry communication.
  3. Inspect and test fuses/relays feeding the suspension ECU; replace any blown fuses.
  4. Visually inspect ECU connector for corrosion, moisture, damaged pins or poor engagement; unplug, inspect and reconnect.
  5. With ignition ON, measure power and ground at the ECU connector pins; verify expected voltages and good chassis ground.
  6. Check CAN bus signals at the ECU connector with a multimeter or scope: verify idle voltages and differential behavior while communicating from a scanner or while other modules are active.
  7. Verify termination resistor across CAN_H and CAN_L (~60Ω). If termination incorrect, trace and repair short/open.
  8. If CAN voltages abnormal, isolate sections of the bus: disconnect the suspension ECU and check if other modules communicate; perform wiggle tests to locate intermittent wiring faults.
  9. If wiring and power/ground/CAN are good but no response, check for ECU wake-up signal from gateway or body control module; review manufacturer service information for wake-up procedure.
  10. If the ECU remains unresponsive, consider replacing or reflashing the ECU per manufacturer procedures. Before replacement, confirm with a known-good module or consult technical service bulletins.

Likely causes

  • Lost power or ground to the pneumatic suspension ECU (fuse, connector, wiring)
  • CAN bus break or short between ECU and gateway (open circuit or incorrect voltages)
  • Connector corrosion or poor contact at the suspension ECU
  • Module internal failure or module asleep and not responding to network wake-up

Fault status

⚠️ Status
Fault — no communication from pneumatic suspension ECU (no signal received).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0100 U0121 U0140 U0155 U0401
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Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

U1124

PEUGEOT U — Network/User

Fault: absence of communication with the pneumatic suspension ECU: No signal

Brand: PEUGEOT
Type: U — Network/User
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse or disabled power supply to the suspension ECU
  • Battery low voltage or poor battery connection
  • Open or shorted wiring to the ECU (power, ground or data lines)
  • Corroded, disconnected or damaged connector at the suspension ECU
  • CAN bus fault (open, short to ground/V+, missing termination)
  • Faulty pneumatic suspension ECU (internal failure)

Symptoms

  • Suspension warning lamp or message on dash
  • Automatic leveling or height adjustment inoperative
  • Compressor not running or no audible activity from suspension ECU
  • Vehicle ride height incorrect or sagging at one or more corners
  • Multiple network communication-related fault codes present
  • Inability of diagnostic scanner to communicate with the suspension ECU

What to check

  • Read all stored DTCs and freeze-frame data with a dedicated diagnostic tool
  • Verify battery voltage (key ON and engine off) — should be ~12–14.5 V
  • Check related fuses and relays for the suspension ECU circuit
  • Visually inspect connectors at the pneumatic suspension ECU for corrosion, bent pins or water ingress
  • Verify presence of other network modules and ability to communicate with them
  • Measure CAN H and CAN L voltages at the ECU connector and at a known-good location

Signal parameters

  • Battery supply to ECU: ~11–14.5 V (key ON); near battery voltage when awake
  • Ground:
  • CAN bus idle voltages (typical): CAN_H ~2.5–3.5 V, CAN_L ~1.5–2.5 V (approx. 2.5 V common-mode)
  • Dominant/active CAN differential voltage up to ~2 V
  • Termination resistance across CAN_H and CAN_L: ~60 ohm (two 120Ω in parallel)

Diagnostic algorithm

  1. Connect a diagnostic scanner and attempt to communicate with the pneumatic suspension ECU; record exact symptoms and stored codes.
  2. Check battery voltage and condition; charge or support battery if low and retry communication.
  3. Inspect and test fuses/relays feeding the suspension ECU; replace any blown fuses.
  4. Visually inspect ECU connector for corrosion, moisture, damaged pins or poor engagement; unplug, inspect and reconnect.
  5. With ignition ON, measure power and ground at the ECU connector pins; verify expected voltages and good chassis ground.
  6. Check CAN bus signals at the ECU connector with a multimeter or scope: verify idle voltages and differential behavior while communicating from a scanner or while other modules are active.
  7. Verify termination resistor across CAN_H and CAN_L (~60Ω). If termination incorrect, trace and repair short/open.
  8. If CAN voltages abnormal, isolate sections of the bus: disconnect the suspension ECU and check if other modules communicate; perform wiggle tests to locate intermittent wiring faults.
  9. If wiring and power/ground/CAN are good but no response, check for ECU wake-up signal from gateway or body control module; review manufacturer service information for wake-up procedure.
  10. If the ECU remains unresponsive, consider replacing or reflashing the ECU per manufacturer procedures. Before replacement, confirm with a known-good module or consult technical service bulletins.

Likely causes

  • Lost power or ground to the pneumatic suspension ECU (fuse, connector, wiring)
  • CAN bus break or short between ECU and gateway (open circuit or incorrect voltages)
  • Connector corrosion or poor contact at the suspension ECU
  • Module internal failure or module asleep and not responding to network wake-up

Fault status

⚠️ Status
Fault — no communication from pneumatic suspension ECU (no signal received).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0100 U0121 U0140 U0155 U0401
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email

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