Code
U131D
CITROEN
U — Network/User
ASR+ selector signal fault: No signal
AI status
Completed
Completed
100%
Causes
- Faulty ASR+/traction control selector switch
- Open or shorted wiring between selector and control module
- Poor or corroded connector at switch or module
- Blown fuse or powered circuit fault supplying the switch/module
- Body/vehicle network (CAN or LIN) communication fault
- Faulty receiving control module (traction/ABS/ESP module)
Symptoms
- ASR/traction control menu or indicator may not respond
- ASR+ selector switch has no effect (cannot enable/disable modes)
- Warning lamp related to traction/ESP/ASR illuminates
- Possible limp-home mode or reduced functionality of traction system
- Diagnostic trouble code U131D stored; no selector input recorded
What to check
- Read and record freeze frame and any additional stored U-codes with a full diagnostic scanner
- Verify vehicle ignition state and attempt to operate the ASR+ selector while watching live data
- Visually inspect switch, harness, and connectors for corrosion, damage or loose pins
- Check relevant fuses and power/ground at switch and receiving module
- Check for CAN/LIN network errors using scan tool (bus-off, error frames, message absence)
- Measure continuity/resistance of wiring between switch and module with ignition off
Signal parameters
- Selector is a digital input: expected state changes when switch operated (open/closed)
- Typical DC voltage at switch: approx. 0 V (closed to ground) or battery voltage (~9–13 V) depending on design — verify against service data
- If communicated over CAN/LIN: periodic message from selector/module present on bus when operated (message frequency typically several Hz)
- Low resistance (
- No high-voltage spikes or excessive noise on supply or signal lines
Diagnostic algorithm
- Connect a capable OBD-II diagnostic tool. Read current and pending codes and check live data for the ASR selector input or related message presence.
- Attempt to operate the ASR+ selector and watch live input/status. If no change, proceed to physical checks.
- Visually inspect the selector switch, its connector, and wiring for damage, corrosion, or disconnection. Repair as needed.
- Check fuses and apply power probe to verify supply voltage at switch connector with ignition ON. Replace blown fuses and repair supply faults.
- Backprobe the switch output pin while operating the switch. Verify expected voltage transitions (per service data). If absent, replace the switch.
- If switch signals are correct but module does not register them, inspect wiring continuity between switch and module pins with ignition OFF. Repair open/shorts.
- Check grounds for the switch and receiving module for low resistance to chassis. Clean and tighten ground connections.
- Scan the vehicle network for CAN/LIN errors. If bus errors exist, isolate bus issue (short, high load, or module fault) and repair.
- If wiring and signals are confirmed good, consider replacing or reprogramming the receiving control module per manufacturer procedure.
- After repairs, clear codes and perform functional test: operate selector through all positions and verify module response and no recurrence of U131D.
Likely causes
- Damaged or disconnected connector at the ASR selector switch
- Faulty switch (mechanical or internal electrical failure)
- Broken wire harness or damaged insulation causing open circuit
- Module not receiving the selector message due to CAN/LIN bus fault
- Loose ground at module or switch causing intermittent/no signal
Fault status
Status
ASR+ selector signal not detected by control module. Check selector switch, wiring, fuses, grounds and vehicle communication bus.
Repair difficulty: Medium
Diagnostic time: 0.5 - 2.0 hours
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