U0268 on 2016 Cadillac CT6: Lost Communication With Side Object Detection Module

What's Unique About the 2016-2016 Cadillac CT6

On the Cadillac CT6 and similar GM sedans, the side object detection modules are located in the corners of the rear bumper. This placement makes them highly susceptible to water, road salt, and debris kicked up by the rear wheels. Over time, moisture can get past the seals and cause corrosion on the module's electronic components or its electrical connector, leading to a communication failure and the U0268 code. This is a common design-related issue across many GM vehicles, with some technicians on forums reporting that certain customers in the salt belt replace these modules almost annually. 🎬 Watch: Why these sensors fail even after being replaced. When the modules become severely corroded, they can get hot enough to be detected with a thermal camera and may even cause a parasitic battery drain or pull down the entire communication bus, leading to no-start conditions.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• "Service Side Blind Zone Alert System" message on the Driver Information Center (DIC)
• "Service Active Safety" message on the DIC
• Blind spot monitoring system is inoperative
• Indicator lights in side mirrors do not illuminate when a vehicle is in the blind spot
• Rear Cross-Traffic Alert system is inoperative
• In some cases, the indicator light on one or both side mirrors may stay illuminated constantly.
• Parasitic battery drain, leading to a dead battery, especially overnight.

Most Likely Causes

1. Failed Side Object Detection Module 🔴 High Probability The module is located in the rear bumper, where it is exposed to moisture and road salt, leading to internal corrosion and failure. The seam between the plastic housing and the back plate is a common entry point for water. This is a well-documented issue on many GM vehicles.
   How to confirm: After removing the rear bumper cover, visually inspect the module for signs of corrosion (white or green powder), swelling of the plastic case, 🎬 See what a water-damaged and corroded module looks like. or water damage. A scan tool will show 'no communication' with the affected module. The module may also be hot to the touch or show up on a thermal camera if it is shorted internally.
   Typical fix: Replace the faulty module and its connector pigtail if corroded. The new module must be programmed by a technician with access to GM's Techline Connect (TIS2Web) software. It is critical to apply dielectric lubricant to the new connector to prevent future moisture intrusion.
   Est. part cost: $150-$450
2. Damaged or Corroded Wiring/Connector 🟡 Medium Probability The same moisture that damages the module can corrode the pins in its electrical connector, causing a poor connection or a complete open circuit. The connector pins are highly susceptible to the 'green death' of corrosion.
   How to confirm: With the module disconnected, inspect the connector terminals for corrosion, bent pins, or broken wires. Perform a continuity and resistance test on the wiring harness. Check for power (12V) and ground (less than 5 ohms resistance) at the connector.
   Typical fix: If the connector is corroded, it must be replaced by splicing in a new pigtail connector. Damaged sections of the harness must be repaired. Sealing the new connector with GM-specified dielectric grease is critical to prevent repeat failure.
   Est. part cost: $25-$60

Rare But Worth Checking

• Faulty Active Safety Control Module: This is the main computer that controls the system. While it can fail, it is much less common than a sensor or wiring issue. This should only be considered after the modules and wiring in the bumper have been thoroughly checked and confirmed to be good.
• Broken Module Mounting Bracket: Per TSB PIT5622B, the modules are mounted on brackets that are heat-staked to the bumper fascia. A minor impact, even one that doesn't leave a visible mark on the bumper, can break these mounts. Over time, the misaligned module learns it cannot see objects correctly and disables itself, which can eventually lead to a communication code.

Diagnosis Steps

1. Scan the vehicle with a professional-grade tool (like the GM MDI 2) to confirm U0268 is present in the Active Safety Control Module.
2. Note which module is not communicating ('Module A' for left, 'Module B' for right). U0268 typically points to the right (passenger) side module.
3. Carefully remove the rear bumper cover to gain access to the side object detection modules located in the corners. This involves removing screws and clips in the wheel wells 🎬 Watch this walkthrough on how to remove the rear bumper. and under the bumper.
4. Visually inspect the module and its electrical connector for any signs of corrosion (green/white powder), water intrusion, or physical damage. Check if the module case is swollen.
5. Inspect the module's mounting bracket for cracks or breaks. Per TSB PIT5622B, even a minor impact can damage the heat-staked mounts, causing misalignment.
6. If corrosion is found, the module and the connector pigtail will need to be replaced.
7. If no visible damage is found, use a multimeter to check for power (approx. 12V on Pin 2) and ground (less than 5 ohms on Pin 5) at the module connector with the ignition on.
8. Test the resistance of the object detection CAN bus. A healthy bus with two 120-ohm terminating resistors should measure approximately 60 ohms between the CAN High and CAN Low pins. A reading of 120 ohms suggests a break in the wiring or that one of the terminating modules is offline.
9. If wiring and mounting are confirmed good, the module itself is the most likely culprit.
10. After replacing parts, the new module must be programmed and calibrated using GM's Service Programming System (SPS).

Parts You'll Likely Need

• Side Object Detection Module (OEM #84612459) — This module is the most common point of failure due to its location in the bumper, which exposes it to moisture and leads to internal corrosion. This part number supersedes previous versions 20968741, 22902467, 22960642, and 84512065.
  Trusted brands: ACDelco, GM Genuine Parts
  OEM price range: $250-$450
  Aftermarket price range: $150-$250
• Module Connector Pigtail (OEM #13343443) — Water intrusion that damages the module almost always corrodes the electrical connector as well. Replacing it is essential for a lasting repair. This connector is also sold under AC Delco part number PT2971 and other aftermarket numbers like CE8031-3.
  Trusted brands: ACDelco, Fleece Performance
  OEM price range: $40-$70
  Aftermarket price range: $25-$50

Related Codes That Often Appear With This One

• U0269 — This code is for 'Lost Communication With Side Object Detection Module A' (typically the left/driver side). It's common for both modules to be exposed to the same conditions, and they may fail around the same time.
• U0075 — This is a more general 'Control Module Communication Bus 'B' Off' code. It can be set alongside U0268, as noted in TSB #PIT5441C, indicating a general problem on the object detection network.

Technical Service Bulletins (TSBs) & Recalls

• PIT5441C: Notes that DTCs U0075, U026A, U026B, U026C, U0265, U0268, and/or U0269 can be set due to a faulty diagnostic interface cable, which can lead to misdiagnosis.
• PIT5622B: Details how broken or misaligned module mounting brackets on the rear fascia can cause the system to become unavailable after a period of driving, even without an obvious impact.
• 16-NA-178: Addresses water intrusion into the module and connector on other GM models, recommending replacement of both modules and the harness if corrosion is found, and application of dielectric lubricant.
• N182181830 (Special Coverage): GM issued a special coverage program for this exact issue (water intrusion causing module failure) on 2013-2017 GMC Acadia, 2014-2015 Impala, and other models, extending the warranty to 6 years/80,000 miles. The CT6 was not included, but it demonstrates GM's acknowledgement of the design flaw.

Platform-Specific Known Issues

• A GM Technical Service Bulletin (TSB #PIT5441C) notes that this code, along with others, can sometimes be falsely set by a faulty diagnostic interface cable used by a technician. This is a diagnostic consideration for the repair shop, not a vehicle fault.
• TSB #PIT5622B describes how a minor bumper impact can break the module's mounting bracket without visible external damage. This causes the module to learn a bad position over a week or so of driving and then disable itself, posting a 'Side Detection System Unavailable' message, sometimes without a DTC.

Mechanic-Grade Diagnostic Values

• Object Detection CAN Bus Resistance — expected: ~60 Ohms. Failure: A reading of ~120 Ohms indicates an open circuit or one of the two terminating modules is offline. A reading significantly below 60 Ohms could indicate a short in the wiring.
• Voltage at Side Object Detection Module Connector — expected: Approximately 12V (Battery Voltage). Failure: Low or no voltage indicates a problem with the power supply wire or a related fuse.
• Ground at Side Object Detection Module Connector — expected: Less than 5 Ohms of resistance to chassis ground.. Failure: High resistance indicates a poor ground connection, which is a common cause of module communication issues.

Scan Tool Commands That Help

• GM GDS2 (Global Diagnostic System 2): Module Diagnostics / Vehicle DTC Information — Used to scan all vehicle modules to confirm which ones are not communicating. For U0268, the Right Side Object Detection Module will typically show as 'Not Responding'.
• GM SPS (Service Programming System): Replace and Program ECU — This function is mandatory after installing a new Side Object Detection Module. It downloads the correct software and vehicle-specific calibration into the new module, linking it to the car's VIN.
• GM GDS2 or equivalent ADAS tool: Side Object Sensor Module Learn/Calibration — After programming a new module, a calibration or learn procedure may be required. This is often done by driving the vehicle under specific conditions to allow the sensor to align and learn its position and environment.

Wiring & Ground Locations

• K124 Active Safety Control Module — Located in the rear compartment, behind the left side trim panel.. This is the master controller for the side detection system. All communication from the side modules routes through this main computer. While failure is rare, a problem here could mimic a sensor issue.
• Side Object Sensor Module Connector — Located in the left and right corners of the vehicle, inside the rear bumper fascia, plugged directly into the radar modules.. This 8-pin connector is the most common failure point besides the module itself. Key pins for testing are Pin 2 (Battery Voltage), Pin 5 (Ground), and Pin 4 (Serial Data). Corrosion here directly causes the U0268 code.
• G400-series Grounds — GM designates grounds in the rear of the vehicle with a '400' series number (e.g., G401, G402). These are typically located on the chassis frame rails in the rear trunk or bumper area.. The side object detection modules rely on a clean chassis ground to function. A corroded or loose ground point in the rear of the vehicle can cause intermittent or total loss of communication.

Real Owner Repair Stories

• CadillacForums.com user report (2014 Cadillac XTS (uses a similar system and parts)) — "Service Driver Assist" message and code U0268.
  ✅ What actually fixed it The owner removed the rear bumper cover and found severe green and white corrosion on the driver's side module and its electrical connector. Replacing both the module and the connector pigtail resolved the code.

OEM Part Supersession History

• 20968741, 22902467, 22960642, 84512065 → 84612459 — Standard part evolution for improved reliability or manufacturing changes.
  Heads up: Used modules are generally not reprogrammable by a GM dealer, as they are often VIN-locked to the original vehicle. A new module is required for a standard dealer repair.