U0159 on 2015-2018 GMC Yukon: Park Assist Communication Failure Causes and Fixes

What's Unique About the 2015-2018 Gmc YUKON

For this specific generation of GMC Yukon and its sister platforms (Tahoe, Suburban, Escalade), GM has acknowledged a common software issue that can randomly trigger a U0159 code at startup. Unlike many other vehicles where this code points directly to a hardware or wiring failure, on these SUVs, the first step is often a simple software re-calibration at the dealership. This is documented in multiple Technical Service Bulletins, making it a known and predictable problem for this platform. Another known issue is a pinched main dash wiring harness 🎬 Watch: Diagnosing U0159 and side detection issues on a Denali, which can cause a host of communication codes including U0159.

Diagnostic Flowchart

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

Symptoms You May Notice

• "Service Parking Assist" message on the Driver Information Center (DIC), often at startup.
• "Park Assist Off" message displayed.
• Parking assist system is completely non-functional.
• Audible chimes and visual distance indicators for parking do not work.
• The warning message may disappear after cycling the ignition off and on.

Most Likely Causes

1. Parking Assist Control Module Software Glitch 🔴 High Probability GM issued TSBs #PIT5507E and #PIT-5507 specifically for this issue on 2015-2018 models, indicating a known software bug that can cause a random communication loss at startup. This is particularly noted for 2016 models but the software update applies to the whole range.
   How to confirm: A GM dealer or a shop with advanced diagnostic tools (like a Tech 2 or MDI) can check the current software calibration version of the Parking Assist Control Module (K41) and compare it against the latest version available in the TIS2WEB database.
   Typical fix: Reprogram the Parking Assist Control Module with the updated calibration. This is a software-only fix performed by a dealer or qualified independent shop.
   Est. part cost: $0
2. Damaged or Corroded Wiring/Connectors 🟡 Medium Probability Modules and wiring harnesses, particularly for side object/cross-traffic sensors, are located behind the rear bumper and wheels, exposing them to water, salt, and road grime, leading to corrosion. The main connector for the rear bumper harness is a common failure point. A pinched dash harness behind the instrument panel is also a known issue on this platform causing various communication codes.
   How to confirm: Visually inspect the wiring harnesses and connectors going to the Parking Assist Control Module (located in the rear quarter panel area) and the individual bumper sensors. Check for green or white corrosion, chafed wires, or loose pins. A scan tool may show a loss of communication with multiple sensors simultaneously.
   Typical fix: Clean the corroded terminals with a contact cleaner or repair/replace the damaged section of the wiring harness. In some cases, the entire rear bumper harness needs to be replaced.
   Est. part cost: $10-$250
3. Failed Parking Sensor or Incorrect Part ⚪ Low Probability Sensors can be damaged by minor bumper impacts or fail internally. Using non-OEM (aftermarket) sensors is a known cause of system malfunction, as the control module may not recognize them. If one sensor fails, the entire system may shut down. Incorrect sensor rings (bezels) can also cause false alerts that may lead to the system shutting down.
   How to confirm: A high-end scan tool can often identify which specific sensor is faulting. A physical inspection may reveal cracks or damage. A simple method is to listen for a faint clicking or buzzing sound from each sensor with the system active; the silent one is likely faulty.
   Typical fix: Replace the faulty sensor with a genuine GM/ACDelco part. Ensure the correct sensor ring (bezel) is used. Aftermarket sensors are strongly discouraged.
   Est. part cost: $50-$150

Rare But Worth Checking

• Failed Parking Assist Control Module (PACM): This module is generally reliable. It should only be considered for replacement after all software, wiring, and sensor issues have been definitively ruled out. The module is located in the rear of the vehicle, often behind the quarter panel trim.
• Blown Fuse: A blown fuse for the park assist system can cause a complete loss of power and communication. On some models, this is fuse #20 (OBS DET) in the driver's side interior fuse panel. Always check your owner's manual for the specific fuse location for your vehicle.

Diagnosis Steps

1. Scan all vehicle modules with a professional-grade scan tool capable of reading BCM, IPC, and PACM codes. Confirm U0159 is active in the BCM or IPC.
2. Check for Technical Service Bulletins (TSBs) related to U0159 for your specific VIN. Specifically look for PIT5507E.
3. If TSB PIT5507E applies, the primary fix is to have a dealer reprogram the Parking Assist Control Module (K41) with the latest software calibration.
4. If the software is up to date or the update does not resolve the issue, perform a thorough visual inspection of the wiring harnesses and connectors to all parking sensors and the control module. Pay close attention to the main harness connector behind the rear bumper and areas behind the rear wheels for corrosion or damage.
5. Check the fuse for the park assist system. For the 2015-2020 generation, this may be fuse F28 in the passenger-side instrument panel fuse block.
6. Using a multimeter, verify that the Parking Assist Control Module is receiving proper power and ground.
7. If a specific sensor is suspected, inspect it for physical damage. Listen for the tell-tale clicking sound from each sensor. Consider swapping it with a known good sensor from another position to see if the fault follows the sensor.
8. Inspect the front park assist sensor rings (bezels) to ensure they are the correct 'scalloped' design (GM part number 84075328) as incorrect rings can cause system faults.
9. If all wiring, sensors, and software are confirmed to be good, the Parking Assist Control Module itself may be faulty.

Parts You'll Likely Need

• Parking Assist Control Module (PACM) Software Update — This is the most common fix, addressing a known software bug that causes random communication loss at startup, as documented in GM TSB PIT5507E.
  Trusted brands: GM (Dealership Service)
  OEM price range: $150-$250
  Aftermarket price range: N/A
• Parking Assist Sensor (OEM #23428268, 23428269) — Individual sensors can fail due to physical damage or internal faults. It is critical to use OEM sensors, as aftermarket versions often cause communication issues. Part number varies by position (inner/outer).
  Trusted brands: ACDelco (GM Genuine)
  OEM price range: $70-$150
  Aftermarket price range: $20-$50
• Parking Sensor Wiring Harness — The harness, especially near the bumpers, is prone to corrosion and damage, which can break the communication line to the module.
  Trusted brands: ACDelco (GM Genuine)
  OEM price range: $100-$250
  Aftermarket price range: $50-$120
• Parking Sensor Ring (Bezel) (OEM #84075328) — Incorrect non-scalloped bezels on front sensors can cause false alerts and system shutdown. This is the updated, correct part.
  Trusted brands: ACDelco (GM Genuine)
  OEM price range: $10-$20
  Aftermarket price range: N/A

Technical Service Bulletins (TSBs) & Recalls

• PIT5507E: Addresses a 'Service Park Assist' message at startup with DTC U0159, recommending a software update for the Parking Assist Control Module. It covers model years 2015-2018.
• PIT-5507: An earlier version of the TSB, also noting that engineering was developing an updated calibration to correct the U0159 concern.

Platform-Specific Known Issues

• A software anomaly can cause a "Service Parking Assist" message and set code U0159 at startup, which may clear after an ignition cycle. This is specifically addressed by TSB PIT5507E.
• Incorrectly designed front park assist sensor rings (bezels) were sometimes installed, causing false alerts and system deactivation. The correct part is a 'scalloped' design, GM part number 84075328.
• Corrosion of the rear radar modules and their connectors, located inside the rear bumper, is common in areas with heavy road salt use, leading to system failure.

Mechanic-Grade Diagnostic Values

• Low-Speed GMLAN Serial Data Line Voltage — expected: Circuit at rest (logic '1'): ~0.2V. Circuit active (logic '0'): Driven to >4.0V.. Failure: Voltage stuck high or low, or not toggling, indicates a short, open, or module failure on the data line.
• Parking Assist Control Module Power Supply — expected: Should be equal to battery voltage (~12.6V with key on, engine off; >13.5V with engine running).. Failure: Low or no voltage indicates a blown fuse, or an open/high resistance in the power feed wire.
• Parking Assist Control Module Ground Circuit Resistance — expected: Less than 5 ohms resistance between the module's ground pin and a known good chassis ground.. Failure: High or infinite resistance (OL) indicates a corroded or broken ground connection.

Scan Tool Commands That Help

• GDS2 (GM Global Diagnostic System 2): Parking Assist Sensor Learn — This function must be performed after replacing a Parking Assist Sensor to ensure the Parking Assist Control Module recognizes the new sensor and calibrates it to the system.

Wiring & Ground Locations

• K41 Parking Assist Control Module — Located in the rear of the vehicle, typically behind the right rear quarter trim panel.. This is the module that is offline. All power, ground, and data line tests are performed at its connector.
• G313 — On the body, underneath the rear seat area.. This is a potential ground point for the rear body harness, which includes the Parking Assist Control Module. A poor connection here can cause communication and power issues for the module.
• Low-Speed GMLAN Serial Data Wire — A single wire (typically Dark Green) running from the BCM to various modules, including the PACM. It is Pin 1 on the DLC.. This is the communication line for the PACM. A short or open on this wire anywhere between the BCM and the PACM will cause code U0159.

Real Owner Repair Stories

• YouTube user video (2015 Cadillac Escalade (K2XX Platform)) — Parking sensors would not work, 'not available' message on screen. If one sensor is broken, the whole system shuts down.
  ❌ Tried (didn't work) Replacing multiple broken sensors with aftermarket (eBay) versions. The system still did not work and threw codes.
  ✅ What actually fixed it After scanning and finding multiple sensor faults persisted, the owner replaced the aftermarket sensors with used, genuine GM sensors. After clearing the codes, the system immediately began working correctly, confirming that non-OEM sensors were the cause of the continued failure.
• YouTube user video (2016 GMC Denali (Yukon)) — 'Service Side Detection' message on DIC.
  ❌ Tried (didn't work) Attempting to clean the heavy corrosion from the module connectors.
  ✅ What actually fixed it The code present was for lost communication with the side detection module. The cause was severe corrosion in the connectors and modules located behind the rear wheels. The final repair was to replace both the wiring harness and the side detection modules themselves, as cleaning the terminals was not sufficient due to deterioration of the plastic connector housing.

OEM Part Supersession History

• 23130107 → 23428268 — Part has been updated by the manufacturer.
  Heads up: The new part number (23428268) is the correct replacement for a wide range of GM vehicles in this era. Using older stock or aftermarket equivalents is known to cause communication failures.
• Unknown (smooth design) → 84075328 (scalloped design) — The original smooth design could cause false alerts, especially in rain or snow. The updated 'scalloped' design resolves this issue.
  Heads up: Using the old, non-scalloped rings on the front bumper can cause the park assist system to deactivate and may contribute to setting communication codes.

Model Year Variations Within This Range

• 2016: TSB PIT5507C specifically calls out 2016 models as being prone to the random 'Service Parking Assist' message at startup with code U0159, which is the primary software glitch concern. While the fix applies to other years, the 2016 models were highlighted as most susceptible.