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Home / DTC / U05C1 — Invalid Data Received From Active Radiator Air Flow Control Module A

U05C1 — Invalid Data Received From Active Radiator Air Flow Control Module A

Detailed page for trouble code U05C1.

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U05C1

Generic U — Network/User

Invalid Data Received From Active Radiator Air Flow Control Module A

Brand: Generic
Type: U — Network/User
Views: UK: 17 EN: 32 RU: 23
AI status
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Page language: EN

Causes

  • Faulty Active Radiator Air Flow Control Module (hardware or internal software error)
  • Damaged wiring or poor connector connection to the module (power, ground, CAN lines)
  • CAN/LIN bus communication fault (bus errors, missing termination, high bit errors)
  • Intermittent power supply or ground to the module
  • Configuration, calibration, or software mismatch after module replacement or update
  • Other module on the bus sending corrupted/invalid messages

Symptoms

  • MIL/Check Engine light or dash warning lamp
  • Radiator shutter or airflow flaps stuck, slow, or unresponsive
  • Abnormal engine temperature regulation (overcooling or overheating)
  • Reduced fuel economy or changed HVAC/engine performance due to cooling control fallback
  • Stored U-codes or other communication DTCs on scan tool
  • Intermittent or permanent loss of data for radiator air flow parameters on scanner

What to check

  • Use a scan tool to read U05C1 code details, freeze frame and related codes; attempt to communicate directly with the radiator air flow control module
  • Inspect module connector and wiring for corrosion, damage, bent pins, or moisture
  • Check module supply voltage (battery +12V) and ground integrity at the connector
  • Check CAN bus for errors: verify CAN High/CAN Low voltages with key on, engine off and scan bus traffic
  • Measure termination resistance across CAN_H and CAN_L (approx. 60 ohms total) with ignition off
  • Check for other U-codes indicating network problems (U0100, U0073, U0401, etc.)

Signal parameters

  • Module supply: typically ~12 V with ignition on; no significant voltage drop under load
  • Module ground: near 0 V; check for high resistance or voltage on ground circuit
  • CAN bus idle (recessive) voltages: ~2.5 V on each CAN line (CAN_H and CAN_L) — measurement should be done with a proper meter or oscilloscope
  • CAN bus dominant state: observable differential between CAN_H and CAN_L when data is transmitted (use oscilloscope to confirm clean frames)
  • Expected CAN data rates: commonly 250 kb/s or 500 kb/s depending on vehicle — verify protocol and data presence with scan tool or scope
  • Termination resistance: about 60 ohms between CAN_H and CAN_L (two 120 ohm terminators in parallel)

Diagnostic algorithm

  1. Record freeze frame and full list of stored codes; note any network-related codes.
  2. Attempt to communicate with the Active Radiator Air Flow Control Module using a manufacturer-capable scan tool. Note whether the module responds and whether data values appear plausible.
  3. Visually inspect the module, connector, and wiring harness for damage, corrosion, water ingress, or disconnected pins. Repair any physical faults.
  4. With ignition on, measure module supply and ground at the connector. Repair high-resistance supply/ground circuits as needed.
  5. Check CAN bus voltages at the module connector: verify recessive voltages (~2.5 V) and presence of data using a scan tool or oscilloscope. Look for excessive bus errors or a bus-off condition.
  6. Measure termination resistance across CAN_H and CAN_L with ignition off; correct missing or incorrect termination.
  7. If wiring and bus are good but communication/data remain invalid, update or reflash module software/calibration per manufacturer service information.
  8. If software update does not restore communication and all vehicle-side checks pass, consider replacing the Active Radiator Air Flow Control Module. Reconnect, clear codes and road/test to confirm repair.
  9. After repair, verify no additional network DTCs and that radiator air flap operation and engine temperature control are normal.

Likely causes

  • Loose/corroded connector at radiator air flow module
  • Open/short on CAN High or CAN Low between module and network
  • Module not receiving stable 12V supply or poor ground
  • Module firmware fault or corrupted configuration
  • Network termination or wiring harness damage localized near radiator area

Fault status

⚠️ Status
Invalid Data Received From Active Radiator Air Flow Control Module A — communication or data integrity fault detected on module A
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours
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