CAN network

U0235 — Lost Communication with Adaptive Cruise Distance Sensor

Severity: medium Safe to drive

What U0235 means

U0235 means a control module lost communication with the front distance sensor (radar or lidar) used by adaptive cruise control. This sensor normally measures the gap and closing speed to the vehicle ahead, and the system uses that data to hold following distance and warn of a collision. Without the signal, those features shut down.

Symptoms

  • Adaptive cruise control unavailable or won't engage
  • Forward collision warning disabled
  • Message on the dash about a radar or ACC fault
  • Driver assist warning light on
  • Other network communication codes may be stored

Possible causes

  1. Failed distance sensor (radar unit)
  2. Sensor misaligned after bumper repair, replacement or impact
  3. Damaged, corroded or open CAN wiring or sensor connector
  4. Dirt, ice or a sticker blocking the sensor (usually sets a different code, but rule it out)
  5. Low supply voltage or poor ground at the sensor
  6. Faulty related control module

How to diagnose

  1. Scan all modules and note freeze frame data and any other U-codes or messages
  2. Inspect the front end: sensor and cover cleanliness, cracks, impact damage, bumper and bracket condition
  3. Check the sensor connector and harness for corrosion, moisture, backed-out pins or damage
  4. Measure power and ground at the sensor connector with the ignition on
  5. Test the CAN High and CAN Low lines for opens, shorts and proper resistance per the wiring diagram
  6. Check battery voltage and terminals and fix any voltage drops
  7. Clear codes and see if U0235 returns and whether the scan tool can see the sensor
  8. Perform sensor calibration or alignment per the manufacturer procedure if needed

Common fixes

  • Clean the sensor and the area in front of it
  • Repair wiring or the connector, restore power and ground
  • Calibrate the radar after bumper or body repair
  • Replace the distance sensor, then calibrate and code it
  • Replace or reflash a faulty control module if it caused the lost communication

Questions and answers

What does U0235 mean?

It means communication was lost with the front distance sensor for adaptive cruise control. The control module isn't receiving radar data, so the feature is turned off.

Can I drive with U0235?

Yes, the car stays drivable, but adaptive cruise and collision warning may not work. Have it fixed soon.

Does the sensor need calibration after bumper repair?

Often yes. Even a small shift in the radar's position distorts its field of view, so it is aligned using the manufacturer's procedure after repair or replacement.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.