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Home / DTC / U041C — Invalid Data Received From Rocker Arm Control Module A

U041C — Invalid Data Received From Rocker Arm Control Module A

Detailed page for trouble code U041C.

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Code

U041C

Generic U — Network/User

Invalid Data Received From Rocker Arm Control Module A

Brand: Generic
Type: U — Network/User
Views: UK: 16 EN: 26 RU: 17
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Page language: EN

Causes

  • Intermittent or failed communication on CAN/LIN network between PCM/scan tool and Rocker Arm Control Module A
  • Damaged wiring harness, broken or corroded connector pins at the rocker arm control module
  • Poor power or ground to the rocker arm control module
  • Faulty rocker arm control module (internal electronics/software)
  • Wrong or incompatible module programming or calibration
  • Missing or improper network termination (open/incorrect resistor)

Symptoms

  • MIL/CEL illuminated and U041C stored
  • Reduced engine performance or limp-home operation (if rocker arm control is essential)
  • Irregular valve timing, rough idle, or misfire-like behavior
  • Intermittent faults that may come and go with vibration or temperature changes
  • Multiple network U-codes present (loss of comms to other modules)

What to check

  • Connect a capable scan tool, read DTCs and freeze frame; note whether code is current or historic
  • Check for other U-codes and modules reporting communication errors
  • Visual inspection of wiring and connectors at the rocker arm control module and along the harness
  • Verify battery voltage and key-on power to the module (check fuses and relays)
  • Check module grounds for tightness and corrosion
  • Measure CAN/LIN bus voltages with a DMM and compare to expected idle levels

Signal parameters

  • CAN bus idle voltages: CANH ≈ 2.5V, CANL ≈ 2.5V (recessive); dominant state: CANH ≈ 3.5V, CANL ≈ 1.5V
  • Expected CAN bus termination: ~60 ohms between CANH and CANL
  • Message frequency: module-specific (often periodic updates between 1–20 Hz); verify expected ID(s) present with a CAN sniffer
  • LIN bus idle ≈ single-wire ~12V (or module specific); check LIN wake/pulse patterns if applicable
  • Error frames or corrupted frames visible on an oscilloscope/CAN log indicate network integrity problems

Diagnostic algorithm

  1. Retrieve and record all DTCs and freeze-frame data; note if U041C is current or intermittent.
  2. Look for associated U-codes or B/C codes that show network-wide problems.
  3. Perform a thorough visual inspection of connector(s) at the rocker arm control module for corrosion, bent pins, pushed-out terminals, or water intrusion; repair as needed.
  4. Verify module supply and grounds with a DMM (battery voltage at power pin with key ON,
  5. Check CAN/LIN bus voltages at the module connector with key ON; compare to expected signal parameters.
  6. Use a CAN sniffer or oscilloscope to confirm the rocker arm control module’s CAN ID/messages are present and not corrupted; look for missing messages, error frames, or abnormal voltages.
  7. Wiggle wiring/harness while monitoring live data to reproduce intermittent communication faults.
  8. Inspect and measure CAN termination resistance (approx. 60 ohms). Remove modules one at a time only if instructed by manufacturer procedures.
  9. If wiring and bus integrity are confirmed, verify module software/calibration level and reflash or update according to OEM procedure; follow safety and anti-theft/programming instructions.
  10. Replace the rocker arm control module only after eliminating harness/network causes. After replacement, program/configure the new module per manufacturer instructions and clear codes, then retest for recurrence.
  11. If problem persists, consult manufacturer technical service information and wiring diagrams or escalate to a specialist with advanced network diagnostic tools.

Likely causes

  • Connector corrosion or bent pins at the rocker arm control module
  • Open/short in CAN high/low or LIN bus between modules
  • Defective rocker arm control module
  • PCM/software mismatch — module needs reprogramming or calibration
  • Missing 60 ohm termination or multiple terminations on the bus

Fault status

⚠️ Status
Invalid data or corrupted messages received from Rocker Arm Control Module A. May be stored as current or intermittent; likely a communication, wiring, power/ground, or module software/hardware fault.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0100 U0121 U0155 U0413 U0422
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