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2020 Audi S5 Sportback - Adaptive Cruise Control Malfunction & Steering Warning

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Tom H. · rep 0 · May 25, 3:10 AM · 1 replies · solved · Question

Vehicle: 2020 Audi S5 Sportback Prestige

Hey everyone, I'm having a weird issue with my 2020 Audi S5 Sportback. Lately, I've been getting an 'Adaptive Cruise Control Malfunction' warning, and sometimes a 'Steering Malfunction' light pops up too. When these warnings appear, the adaptive cruise control, lane assist, and sometimes even the regular cruise control stop working.

I ran a scan, and I'm seeing a C1101 code, which seems to relate to the 'Distance Sensor' or 'ACC Sensor'. I also saw a U0415 code for 'Invalid Data Received from ABS Control Module'. It's intermittent, but it's happening more frequently now, especially in wet weather.

Could this be a sensor alignment issue, or something more serious with the radar unit? I've checked the front grille area for obvious obstructions, but found nothing. Any thoughts?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:10 AM

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ClearTheCode admin answer:

An 'Adaptive Cruise Control Malfunction' combined with a 'Steering Malfunction' and the C1101 (Distance Sensor) and U0415 (Invalid Data from ABS) codes on your 2020 Audi S5 Sportback points to a complex issue involving multiple driver-assistance systems. These systems are highly integrated and rely on accurate data from various sensors.

Here's a breakdown of potential causes and diagnostic steps:

  1. ACC Radar Sensor (C1101): The C1101 code specifically indicates an issue with the Adaptive Cruise Control radar sensor, typically located behind the front grille or bumper. Potential issues include:
    • Misalignment: Even a slight bump or minor impact can knock the sensor out of calibration, requiring a specialized alignment procedure.
    • Obstruction/Damage: While you checked for obvious obstructions, internal damage to the sensor unit itself or wiring issues can occur. Road debris, even small stones, can impact the sensor face.
    • Contamination: Dirt, ice, or heavy rain can temporarily obscure the sensor, which you've noted happens more in wet weather. However, persistent issues suggest more than just temporary blockage.
  2. ABS Control Module Communication (U0415): The U0415 code suggests a communication problem with the ABS control module. The ACC system relies heavily on wheel speed data from the ABS module. If the ACC isn't receiving valid speed data, it will fault. This could be due to:
    • Faulty Wheel Speed Sensor: A failing wheel speed sensor can send incorrect data to the ABS module, which then relays bad data to other systems.
    • ABS Module Internal Fault: Less common, but the ABS control module itself could have an internal fault or a power/ground issue.
    • CAN-Bus Communication: A broader issue with the vehicle's CAN-Bus network could be disrupting communication between modules.
  3. Steering Angle Sensor: The 'Steering Malfunction' often accompanies ACC issues because lane assist and adaptive cruise control require accurate steering angle data. While not directly coded, a related issue could be present.

When to see a shop:

  • Immediately. Due to the complexity of these integrated systems and the need for specialized calibration, professional diagnosis is essential. An Audi dealership or a high-end independent shop with Audi diagnostic capabilities (ODIS) is required.
  • They can perform a full system scan, check live data from all relevant sensors (ACC radar, wheel speed sensors, steering angle sensor), and identify precisely which component is failing or if a recalibration is needed.
  • Attempting to fix these issues without the proper tools and knowledge can be very difficult and potentially lead to further complications. Given the safety implications of ACC and steering systems, it's best left to experts.
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