Code
U0240
Generic
U — Network/User
Lost Communication With Entrapment Control Module B
AI status
Completed
Completed
100%
Causes
- Open or short in CAN/communication wiring (CAN High/CAN Low or LIN where applicable)
- Faulty or unpowered Entrapment Control Module B (no Vb or ground)
- Corroded/damaged connector or poor pin contact at the module
- Blown fuse or relay that supplies the module
- Network termination or bus fault (short to battery/ground, missing termination)
- Software/firmware mismatch or failed module initialization
Symptoms
- DTC U0240 stored in scan tool
- Related features disabled (anti-entrapment, power window/closer functions)
- Instrument cluster or message center may display a communication/warning message
- Intermittent operation of affected systems or functions
- Other network modules reporting related U-codes or loss of communication
What to check
- Read and record all U-codes and freeze frame data with a capable scan tool
- Check for presence of Entrapment Control Module B in the module list via scanner
- Visually inspect connectors, pins and wiring at the module and along harness runs for damage, corrosion or water intrusion
- Check fuses and relays that supply the module for continuity and proper voltage
- Measure supply voltage and ground at the module connector with key on (refer to vehicle spec)
- Check CAN bus voltage at the module: measure CAN_H and CAN_L with key on, engine off
Signal parameters
- CAN idle voltages (typical): CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (each ~2.5V when recessive); dominant state: CAN_H ~3.5 V, CAN_L ~1.5 V (values vary by vehicle)
- Expected bus bit rates: commonly 250 kbps or 500 kbps depending on vehicle network
- Termination resistance: approx. 60 ohms measured between CAN_H and CAN_L (two 120Ω in parallel ≈ 60Ω)
- Module supply voltage: battery voltage present at Vb pin with key on (vehicle-specific)
Diagnostic algorithm
- Connect a capable scan tool and confirm U0240 and any related U-codes; record freeze frame and occurrence conditions
- Verify the Entrapment Control Module B is listed/responding on the network. If not present, proceed.
- Visually inspect and secure the module connector; look for bent pins, corrosion, moisture, or damage. Repair as needed.
- Check fuses/relays for the module circuit; replace if blown and retest.
- With key on (engine off), measure module supply voltage and ground at the connector. If no power or ground, trace and repair open circuit.
- With key on, measure CAN_H and CAN_L at the module connector. Compare to expected values and to another known-good module location. Look for short to ground or battery on either line.
- Measure termination resistance between CAN_H and CAN_L with power off; expect ~60 ohms. If open or out of range, inspect/repair termination resistors or wiring.
- If bus voltages are abnormal, isolate sections of the bus by disconnecting suspected nodes (per manufacturer procedure) to identify a shorted module or harness segment.
- If wiring and power checks are good but module does not respond, attempt reprogramming/initialization per manufacturer procedures if applicable.
- If all wiring, bus integrity and power are confirmed and reprogramming does not restore communication, replace the Entrapment Control Module B as a last step.
- After repair, clear codes and verify proper communication and operation; road test or exercise affected features to confirm stability.
Likely causes
- Disconnected or corroded connector at Entrapment Control Module B
- Broken or chafed CAN wires in door harness or body harness
- Blown fuse supplying the module
- Failed module (internal electronics)
- Short to ground or battery on CAN_H or CAN_L due to wire damage or water intrusion
Fault status
Status
Lost Communication With Entrapment Control Module B — module not responding on the vehicle network (CAN/LIN).
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
Repair manuals
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Code
U0240
HYUNDAI
U — Network/User
Lost Communication With Entrapment Control Module “B”
AI status
Completed
Completed
100%
Causes
- Open or short in CAN/communication wiring (CAN High/CAN Low or LIN where applicable)
- Faulty or unpowered Entrapment Control Module B (no Vb or ground)
- Corroded/damaged connector or poor pin contact at the module
- Blown fuse or relay that supplies the module
- Network termination or bus fault (short to battery/ground, missing termination)
- Software/firmware mismatch or failed module initialization
Symptoms
- DTC U0240 stored in scan tool
- Related features disabled (anti-entrapment, power window/closer functions)
- Instrument cluster or message center may display a communication/warning message
- Intermittent operation of affected systems or functions
- Other network modules reporting related U-codes or loss of communication
What to check
- Read and record all U-codes and freeze frame data with a capable scan tool
- Check for presence of Entrapment Control Module B in the module list via scanner
- Visually inspect connectors, pins and wiring at the module and along harness runs for damage, corrosion or water intrusion
- Check fuses and relays that supply the module for continuity and proper voltage
- Measure supply voltage and ground at the module connector with key on (refer to vehicle spec)
- Check CAN bus voltage at the module: measure CAN_H and CAN_L with key on, engine off
Signal parameters
- CAN idle voltages (typical): CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (each ~2.5V when recessive); dominant state: CAN_H ~3.5 V, CAN_L ~1.5 V (values vary by vehicle)
- Expected bus bit rates: commonly 250 kbps or 500 kbps depending on vehicle network
- Termination resistance: approx. 60 ohms measured between CAN_H and CAN_L (two 120Ω in parallel ≈ 60Ω)
- Module supply voltage: battery voltage present at Vb pin with key on (vehicle-specific)
Diagnostic algorithm
- Connect a capable scan tool and confirm U0240 and any related U-codes; record freeze frame and occurrence conditions
- Verify the Entrapment Control Module B is listed/responding on the network. If not present, proceed.
- Visually inspect and secure the module connector; look for bent pins, corrosion, moisture, or damage. Repair as needed.
- Check fuses/relays for the module circuit; replace if blown and retest.
- With key on (engine off), measure module supply voltage and ground at the connector. If no power or ground, trace and repair open circuit.
- With key on, measure CAN_H and CAN_L at the module connector. Compare to expected values and to another known-good module location. Look for short to ground or battery on either line.
- Measure termination resistance between CAN_H and CAN_L with power off; expect ~60 ohms. If open or out of range, inspect/repair termination resistors or wiring.
- If bus voltages are abnormal, isolate sections of the bus by disconnecting suspected nodes (per manufacturer procedure) to identify a shorted module or harness segment.
- If wiring and power checks are good but module does not respond, attempt reprogramming/initialization per manufacturer procedures if applicable.
- If all wiring, bus integrity and power are confirmed and reprogramming does not restore communication, replace the Entrapment Control Module B as a last step.
- After repair, clear codes and verify proper communication and operation; road test or exercise affected features to confirm stability.
Likely causes
- Disconnected or corroded connector at Entrapment Control Module B
- Broken or chafed CAN wires in door harness or body harness
- Blown fuse supplying the module
- Failed module (internal electronics)
- Short to ground or battery on CAN_H or CAN_L due to wire damage or water intrusion
Fault status
Status
Lost Communication With Entrapment Control Module B — module not responding on the vehicle network (CAN/LIN).
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
Repair manuals
Manual library for HYUNDAI
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