U0265 on 2017-2018 GMC Acadia: Side Detection Module Communication Failure Causes & Fixes

What's Unique About the 2017-2018 Gmc ACADIA

On this generation of the GMC Acadia (and its C1XX platform mates like the Cadillac XT5), the side obstacle detection modules are notoriously prone to failure. Their location inside the rear bumper fascia exposes them to water, road salt, and debris kicked up by the tires. The seals on the module housing can fail, allowing moisture to seep into the module's housing and past the connector. This leads to severe corrosion on the internal circuit board and connector pins, which is the root cause of this code in the vast majority of cases. GM acknowledged this widespread issue with a Special Coverage program for some model years.

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 Detection System" message on the Driver Information Center (DIC).
🎬 Watch: What this warning message looks like on your dashboard.
• Blind spot warning light in the side mirror is always on or never illuminates.
• Rear Cross-Traffic Alert system is disabled.
• In some cases, a shorted module can cause a parasitic battery drain, leading to a dead battery.
• In rare cases of severe module shorting, it can cause other network problems like loss of instrument cluster functions, radio/display issues, or other random warning lights as the CAN bus gets corrupted.

Most Likely Causes

1. Failed Side Obstacle Detection Module (Right Side) 🔴 High Probability The module is located in the rear bumper corner, where it is highly vulnerable to water intrusion from rain, car washes, and road spray. The plastic housing's seal can fail, allowing moisture to corrode the internal circuit board and connector pins. This is a well-documented design flaw across many GM models.
   How to confirm: Remove the rear bumper cover 🎬 See this walkthrough on accessing and replacing the radar modules. and visually inspect the module and its connector for signs of green or white corrosion, swelling, or water marks. A scan tool will show no communication with the module. Often, the module will be physically swollen or cracked from the corrosion inside.
   Typical fix: Replace the faulty module. The new module must be programmed by a dealer or qualified shop using GM's Service Programming System (SPS). If the connector is also corroded, it must be replaced. Applying dielectric grease to the new connector is highly recommended to prevent future moisture intrusion.
   Est. part cost: $150-$350
2. Damaged Wiring or Connector 🟡 Medium Probability The wiring harness and connector are also located in the rear bumper area and can be damaged by moisture, impacts, or road debris. The connector pins are often the first point of failure from water wicking into the module.
   How to confirm: With the bumper cover removed, inspect the wiring harness leading to the module for broken wires, chafing, or corroded pins in the connector. Check for 12V power, good ground, and CAN bus signals at the connector with a multimeter.
   Typical fix: Repair the damaged section of the wiring harness or replace the connector pigtail. Apply dielectric grease to the new connector to prevent future moisture intrusion. In severe cases, the entire rear body harness may need replacement.
   Est. part cost: $20-$150
3. False Code from Diagnostic Tool ⚪ Low Probability TSB #PIT5441C notes that a faulty MDI (Multiple Diagnostic Interface) cable used by technicians can cause false communication codes, including U0265, to be set. The issue stems from a problem with the cable's connection to the specific pins (3 and 11) used for the object detection bus.
   How to confirm: A technician would test their diagnostic tool on a known-good vehicle or use a self-test adapter (EL-47955-1) to verify the tool's integrity before diagnosing the vehicle. If the tool sets similar codes on a good vehicle, the tool's cable is the problem.
   Typical fix: If the tool is faulty, use a different, known-good diagnostic tool. The code on the vehicle was likely a false positive and no parts need to be replaced.
   Est. part cost: $0

Rare But Worth Checking

• Water Intrusion at Body Connectors:

Diagnosis Steps

1. If you are a technician, first follow the advice of TSB #PIT5441C and verify your MDI diagnostic cable is not the cause of the code by testing on a known-good vehicle or using a loopback adapter.
2. Check for GM Special Coverage N172097060, which covers this exact issue for 2017 models up to 6 years/80,000 miles. If eligible, the repair should be performed by a dealer at no cost. Note that this program expired for most 2017 models around 2023.
3. Scan the vehicle for all DTCs. Note if U0265 is current or history, and if any other communication codes are present.
4. Remove the rear bumper fascia to gain access to the side obstacle detection modules.
5. Visually inspect the right-side module (and left side, U026A) and its electrical connector for any signs of physical damage, green or white corrosion, or water stains. The module housing may be swollen or cracked.
6. If corrosion is evident, the module and likely the connector pigtail need to be replaced.
7. If there is no visible damage, use a multimeter to test for 12V power, good ground, and check the integrity of the two CAN bus communication wires at the module's connector.
8. If power, ground, and wiring are confirmed to be good, the module itself has failed internally and requires replacement.
9. After replacing the module and/or connector, apply dielectric grease to the connector pins to protect against future moisture.
10. After installation, the new module must be programmed using GM's Service Programming System (SPS) software for the system to function.

Parts You'll Likely Need

• Side Obstacle Detection Control Module (Right) (OEM #42625293) — This is the component that fails most often due to water intrusion, causing the U0265 code.
  Trusted brands: ACDelco (GM Genuine)
  OEM price range: $200-$350
  Aftermarket price range: $150-$250
• Side Obstacle Detection Control Module (Left) (OEM #42625292) — If the left side fails concurrently or sets code U026A, this part will be needed. They often fail around the same time due to similar exposure.
  Trusted brands: ACDelco (GM Genuine)
  OEM price range: $200-$350
  Aftermarket price range: $150-$250
• Blind Spot Detection Sensor Connector (OEM #CONB11357 (Duralast), S2507 (Standard Motor Products)) — If the module is corroded, the connector pigtail is almost always damaged as well and should be replaced to ensure a lasting repair. This is an 8-pin connector.
  Trusted brands: Duralast, Standard Motor Products (SMP), ACDelco
  OEM price range: $25-$50
  Aftermarket price range: $15-$30

Related Codes That Often Appear With This One

• U026A — This code is for 'Lost Communication With Side Obstacle Detection Control Module 'A' (Left)'. It's common to see both left and right side module codes together if there is a widespread wiring issue or if both modules have failed from similar water exposure.

Technical Service Bulletins (TSBs) & Recalls

• PIT5441C: Advises technicians that U0265 and other object detection codes can be falsely triggered by a faulty MDI diagnostic cable, and to rule this out before proceeding with vehicle repairs.
• N172097060: A Special Coverage program (similar to a warranty extension) for 2013-2017 GMC Acadia models to replace failed Side Blind Zone Alert modules caused by water intrusion at no charge within 6 years/80,000 miles.
• PIT5606J: Details potential water intrusion into major body connectors (X500, X600, etc.) on the 2017-2021 Acadia/XT5 due to clogged drains or bad body plugs, which can cause widespread electrical and communication faults.

Platform-Specific Known Issues

• Special Coverage N172097060: GM issued this program for 2013-2017 GMC Acadia models (among others) to cover the failure of the Side Blind Zone Alert modules due to water intrusion. It covered r

Mechanic-Grade Diagnostic Values

• Low-Speed GMLAN Bus Resistance — expected: The side obstacle detection modules communicate on a single-wire Low-Speed GMLAN bus. The circuit should toggle between 0-5V during communication.. Failure: A static voltage, or voltage outside the 0-5V range, indicates a short or open in the circuit. Resistance to ground should be greater than 100 ohms with the ignition off.
• High-Speed GMLAN Bus Resistance (for general network check) — expected: Approximately 60 ohms when measured across pins 6 and 14 of the DLC with the battery disconnected. This confirms the two 120-ohm terminating resistors are intact.. Failure: A reading of ~120 ohms indicates an open circuit to one of the terminating resistors. A reading of 0 ohms indicates the CAN+ and CAN- wires are shorted together.

Hidden / Shadow Codes Worth Checking

• U0140, U1608, or U1610 in FCM: In some rare cases, software anomalies in the B174W Front Camera Module (FCM) can cause it to set DTC U0265 in the Instrument Panel Cluster (IPC), along with these other codes in the FCM itself. (see via A professional scan tool like the GM GDS2 is needed to read codes from individual modules like the Front Camera Module.)

Scan Tool Commands That Help

• GDS2 (GM Global Diagnostic System 2): Module Setup / Programming — This function is mandatory after replacing a Side Obstacle Detection Module. The new module must be programmed to the vehicle's VIN and calibrated using the Service Programming System (SPS) within GDS2 for it to be recognized and function correctly.
• GDS2 (GM Global Diagnostic System 2): Vehicle DTC Information / Module Diagnostics — Used during initial diagnosis to perform a full vehicle scan. If the Side Obstacle Detection Module does not appear on the list of scanned modules, it confirms a total loss of communication, pointing towards a power, ground, or complete wiring failure rather than an intermittent fault.

Wiring & Ground Locations

• Low-Speed GMLAN Bus at DLC — Pin 1 of the Data Link Connector (DLC) under the driver's side dashboard.. This is the primary communication wire for the side obstacle detection system. A technician can test the circuit's integrity at this easily accessible point before accessing the modules in the rear bumper.
• Rear Bumper Main Harness Connector — Located inside the rear bumper, this is the main connector that feeds the entire rear bumper assembly, including both side detection modules and parking sensors.. This connector is a known failure point. Wires, specifically the pink and green communication wires, can corrode and break right at the connector, causing a complete loss of communication to both modules.
• G401 — Near the base of the left 'D' pillar (the rearmost pillar of the vehicle).. This is a primary ground point for several components in the rear of the vehicle, including the 'Left Side Object Sensor' on some models. A loose or corroded G401 could cause communication issues for rear-mounted modules.
• Module Connector — Plugs directly into the side obstacle detection module inside the rear bumper corners.. This is an 8-pin connector that is the most common point of failure due to water intrusion wicking past the seal, causing severe corrosion on the pins and in the module itself.

Real Owner Repair Stories

• YouTube channel 'Crown Collision Solutions' (2017 GMC Terrain (mechanically similar platform)) — No communication with either Side Object Detection module; the scan tool acted as if the vehicle was not equipped with the feature. No DTCs were present because the modules were completely offline.
  ❌ Tried (didn't work) Checking fuses (all were good)., A body shop had already replaced the left side module with no change.
  ✅ What actually fixed it The technician removed the rear bumper and found two broken wires (pink and green) at the main wiring harness connector for the rear bumper assembly. The wires had corroded and broke with a light touch. The entire rear bumper wiring harness was replaced to resolve the issue.
• YouTube channel 'Pine Hollow Auto Diagnostics' (2018 Chevrolet Traverse (C1XX platform sibling)) — "Service Side Detection System" message, blind spot lights on mirrors constantly illuminated. No communication with either side object detection module.
  ❌ Tried (didn't work) Packing the corroded connector with dielectric grease by a previous shop.
  ✅ What actually fixed it Upon inspection, the left side module connector was full of water. The right side module was held in with a zip tie. Both modules were visibly swollen and corroded. The final fix was replacing both the left and right side object detection modules AND the rear bumper wiring harness that connects to them.

OEM Part Supersession History

• 23350575, 23395663, 23395664, 42358266, 84121022, 84121023 → 42625293 — Standard part evolution, likely for improved sealing or electronics.
  Heads up: This is the history for the Right (Passenger) Side module. The latest part number is the correct replacement.
• 23163923, 23395350, 23395351, 84121020, 84121021 → 42625292 — Standard part evolution, likely for improved sealing or electronics.
  Heads up: This is the history for the Left (Driver) Side module. The latest part number is the correct replacement.