Code
U041D
Generic
U — Network/User
Invalid Data Received From Rocker Arm Control Module B
Views:
UK: 16
EN: 28
RU: 14
AI status
Completed
Completed
100%
Causes
- Rocker Arm Control Module B generating corrupt or out-of-range messages
- Faulty module power supply or ground
- Damaged or corroded connector or wiring between module and network
- CAN/LIN bus wiring fault, bad termination, or excessive noise
- ECU/software mismatch or incorrect calibration
- Intermittent connection (loose connector, broken wire)
Symptoms
- Malfunction Indicator Lamp (MIL) or network warning light illuminated
- Reduced engine performance or limp-home mode if valve control is affected
- Rough idle or misfire-like symptoms under some conditions
- Stored or accompanying DTCs related to valve actuation, CAN bus, or other modules
- Possible abnormal noises from valvetrain if actuator not commanded correctly
- Failure of some driveability or emissions-related systems to operate
What to check
- Read all stored and pending DTCs from all modules and record freeze-frame data
- Verify the presence and frequency of Rocker Arm Control Module B messages with a capable scan tool or CAN bus analyzer
- Check battery voltage and measure module 12V supply and ground continuity
- Inspect module connector for corrosion, bent pins, water ingress or damage
- Visually inspect CAN/LIN wiring for chafing, repairs, or shorts to chassis
- Measure CAN high/low voltages with key on engine off (expect ~2.5V differential, bus recessive ~2.5V each)
Signal parameters
- CAN message presence: rocker arm module should transmit its status message at a regular rate (typical 1–50 Hz depending on manufacturer)
- CAN bus physical levels: CAN_H ~2.5V (idle) rising toward ~3.5V dominant, CAN_L ~2.5V (idle) falling toward ~1.5V dominant
- Bus termination: two 120 Ω resistors in parallel => ~60 Ω across CAN_H and CAN_L
- Module supply: battery voltage near 12V with ignition on; verify 5V reference if module requires
- Message content: expected parameter ranges include actuator position/status codes; invalid data typically out of expected numeric range or checksum/CRC fail
Diagnostic algorithm
- Retrieve all DTCs and freeze frame data from all modules. Note any related U-/P-/B-/C-codes.
- Attempt to communicate directly with Rocker Arm Control Module B using factory or professional scan tool. Note if module responds and its reported software/calibration level.
- Check module power and ground: measure 12V supply and ground resistance to chassis. Repair any faults before proceeding.
- Inspect connector pins and wiring at the module. Repair or replace damaged connector/harness as required.
- Use a CAN bus scanner or oscilloscope to verify message presence, correct voltage levels, and message frequency. Check termination resistance (~60 Ω).
- Perform a wiggle test on harness and connectors while monitoring live data to isolate intermittent faults.
- If wiring and power/ground are good but data is invalid, try reflashing module software per factory procedure or reprogram the ECM if advised by manufacturer guidance.
- If available, swap with a known-good module (or bench-test module) or substitute a repaired module to confirm module failure before replacement.
- Clear codes and road-test to confirm repair. Monitor for reoccurrence and for any related fault codes that appear afterward.
- If intermittent, consider harness repair, securing connectors, or installing shielding to reduce EMI.
Likely causes
- Loose or corroded connector at Rocker Arm Control Module B
- Open/shorted CAN high/low or high impedance on bus (missing termination)
- Module supply (12V) missing or low, or poor ground
- Module firmware corrupted or incompatible after an update
- Intermittent wiring break or pin damage on harness
Fault status
Status
Control module B transmitted data that the receiving module deemed invalid (out-of-range, format error, checksum/CRC failure, or unexpected values). The vehicle network recorded U041D when the message failed validation.
Repair difficulty: Medium
Diagnostic time: 1-4 hours
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Code
U041D
HYUNDAI
U — Network/User
Invalid Data Received From Rocker Arm Control Module “B”
Views:
UK: 13
EN: 13
RU: 9
AI status
Completed
Completed
100%
Causes
- Rocker Arm Control Module B generating corrupt or out-of-range messages
- Faulty module power supply or ground
- Damaged or corroded connector or wiring between module and network
- CAN/LIN bus wiring fault, bad termination, or excessive noise
- ECU/software mismatch or incorrect calibration
- Intermittent connection (loose connector, broken wire)
Symptoms
- Malfunction Indicator Lamp (MIL) or network warning light illuminated
- Reduced engine performance or limp-home mode if valve control is affected
- Rough idle or misfire-like symptoms under some conditions
- Stored or accompanying DTCs related to valve actuation, CAN bus, or other modules
- Possible abnormal noises from valvetrain if actuator not commanded correctly
- Failure of some driveability or emissions-related systems to operate
What to check
- Read all stored and pending DTCs from all modules and record freeze-frame data
- Verify the presence and frequency of Rocker Arm Control Module B messages with a capable scan tool or CAN bus analyzer
- Check battery voltage and measure module 12V supply and ground continuity
- Inspect module connector for corrosion, bent pins, water ingress or damage
- Visually inspect CAN/LIN wiring for chafing, repairs, or shorts to chassis
- Measure CAN high/low voltages with key on engine off (expect ~2.5V differential, bus recessive ~2.5V each)
Signal parameters
- CAN message presence: rocker arm module should transmit its status message at a regular rate (typical 1–50 Hz depending on manufacturer)
- CAN bus physical levels: CAN_H ~2.5V (idle) rising toward ~3.5V dominant, CAN_L ~2.5V (idle) falling toward ~1.5V dominant
- Bus termination: two 120 Ω resistors in parallel => ~60 Ω across CAN_H and CAN_L
- Module supply: battery voltage near 12V with ignition on; verify 5V reference if module requires
- Message content: expected parameter ranges include actuator position/status codes; invalid data typically out of expected numeric range or checksum/CRC fail
Diagnostic algorithm
- Retrieve all DTCs and freeze frame data from all modules. Note any related U-/P-/B-/C-codes.
- Attempt to communicate directly with Rocker Arm Control Module B using factory or professional scan tool. Note if module responds and its reported software/calibration level.
- Check module power and ground: measure 12V supply and ground resistance to chassis. Repair any faults before proceeding.
- Inspect connector pins and wiring at the module. Repair or replace damaged connector/harness as required.
- Use a CAN bus scanner or oscilloscope to verify message presence, correct voltage levels, and message frequency. Check termination resistance (~60 Ω).
- Perform a wiggle test on harness and connectors while monitoring live data to isolate intermittent faults.
- If wiring and power/ground are good but data is invalid, try reflashing module software per factory procedure or reprogram the ECM if advised by manufacturer guidance.
- If available, swap with a known-good module (or bench-test module) or substitute a repaired module to confirm module failure before replacement.
- Clear codes and road-test to confirm repair. Monitor for reoccurrence and for any related fault codes that appear afterward.
- If intermittent, consider harness repair, securing connectors, or installing shielding to reduce EMI.
Likely causes
- Loose or corroded connector at Rocker Arm Control Module B
- Open/shorted CAN high/low or high impedance on bus (missing termination)
- Module supply (12V) missing or low, or poor ground
- Module firmware corrupted or incompatible after an update
- Intermittent wiring break or pin damage on harness
Fault status
Status
Control module B transmitted data that the receiving module deemed invalid (out-of-range, format error, checksum/CRC failure, or unexpected values). The vehicle network recorded U041D when the message failed validation.
Repair difficulty: Medium
Diagnostic time: 1-4 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
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