B2462 on 2015-2018 GMC Sierra Denali: GPS Antenna Fault, Causes, and Fixes

What's Unique About the 2015-2018 Gmc SIERRA DENALI

This generation of GM trucks and SUVs (K2XX platform) is notorious for this specific issue due to the design of the roof-mounted 'shark fin' antenna. The gasket at the base of the antenna frequently fails, allowing water to leak into the vehicle and, more importantly, into the antenna's internal electronics. A design flaw in the original antenna placed a drain hole in a position where it trapped water, while the updated part moves the drain to the bottom to allow water to escape. This water intrusion corrodes the circuit board, leading to the B2462 fault. 🎬 Watch: How this antenna design flaw causes water leaks. The problem is so common that GM has issued multiple Technical Service Bulletins (TSBs), including #17NA214 and #PIT5362B, acknowledging the issue and outlining the repair.

Diagnostic Flowchart

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

Symptoms You May Notice

• Inaccurate GPS location, a GPS symbol with a slash through it, or "No GPS" message on the navigation display.
• SiriusXM satellite radio has "No Signal" or cuts out frequently, especially after a car wash or rain.
• Red LED light on the OnStar button, or inability to connect to OnStar services.
• Visible water stains on the headliner, especially near the sun visors or overhead console.
• A weak or dead battery, which can happen if the water leak shorts out other electronics like the fuse box in the A-pillar.

Most Likely Causes

1. Failed Roof 'Shark Fin' Antenna 🔴 High Probability The gasket at the base of the antenna is prone to failure, and a design flaw in the original part traps water inside the housing, corroding the internal circuit board. GM acknowledged this in TSBs and released an updated antenna design with a relocated drain hole to mitigate this.
   How to confirm: Check for water stains on the headliner below the antenna. Scan for codes B2462, B2470, or B125C. If symptoms and codes are present, the antenna has almost certainly failed. Upon removal, the internal circuit board will often show visible green or white corrosion and rust.
   Typical fix: Replace the entire roof antenna assembly. It is critical to clean the roof surface and apply a bead of automotive-grade clear seam sealer (like Kent Automotive High-Tech Clear Seam Sealer) around the new antenna's base during installation to prevent future leaks, as recommended by TSB #17NA214.
   Est. part cost: $80-$180

Rare But Worth Checking

• Damaged Coaxial Cable: The cable running from the antenna to the radio module could be pinched, disconnected, or damaged, though this is much less common than the antenna itself failing. This would typically only happen if the headliner or other trim was recently removed. GM offers coaxial cable repair kits to service damaged cables without full replacement.
• Clogged Sunroof Drains: In some cases, water stains on the headliner are caused by clogged sunroof drains, which can mimic the symptoms of a leaking antenna. If you have a sunroof, it's worth checking the drains as a possible related issue, though this will not cause code B2462 directly.
• Failed OnStar Module: In very rare instances, even after replacing the antenna, GPS functionality may not be restored. Some owners have reported that a failed OnStar/VCIM module was the final piece of the puzzle, though this should be considered only after the antenna has been replaced.

Diagnosis Steps

1. Confirm symptoms: Check for non-functional GPS (often with a slashed icon), XM radio, or OnStar (red light).
2. Inspect the headliner: Carefully check for any water stains or dampness on the headliner, particularly around the overhead console and sun visors.
3. Scan for codes: Use an OBD-II scanner to confirm the presence of B2462. Note if B2470 or B125C are also present, as this strongly indicates antenna failure.
4. Access the antenna: To perform the replacement, partially lower the headliner. This typically involves removing the driver-side A-pillar cover (10mm bolts), sun visor (T15 Torx screws), and grab handle.
5. Inspect antenna and connectors: Unbolt the single 10mm nut holding the antenna. Check the connectors for green or white signs of corrosion. When the old antenna is removed, it will often be full of water.
6. Prioritize antenna replacement: Given the high failure rate documented in TSBs, if symptoms and codes are present, the most direct diagnostic step is to replace the antenna assembly.

Parts You'll Likely Need

• High Frequency Antenna Assembly (OEM #84544243 (superseded by 84544674, among others)) — This is the complete 'shark fin' unit that fails due to internal water damage. The original part has a design flaw, and replacing it with the updated version is the definitive fix. Note: Part numbers are frequently superseded and vary by vehicle color and options; always verify with a VIN. The earliest TSB (PIT5362B) mentions a switch to pre-painted antennas.
  Trusted brands: ACDelco, GM Genuine Parts
  OEM price range: $80-$180
  Aftermarket price range: $50-$100
• Clear Automotive Seam Sealer — Explicitly recommended by GM in TSB #17NA214 to apply around the new antenna's seal to prevent a repeat failure from water intrusion. This is a critical step for a durable repair. Note: The earlier TSB PIT5362B from 2015 advised *against* using sealants, but the later 2018 TSB recommends it, showing an evolution in GM's repair strategy.
  Trusted brands: Kent Automotive High-Tech Clear Seam Sealer, 3M
  OEM price range: $20-$30
  Aftermarket price range: $15-$25

Related Codes That Often Appear With This One

• B2470 — This code relates to the cellular antenna, which is housed in the same 'shark fin' assembly. A water leak often damages both the GPS and cellular circuits simultaneously.
• B125C — This is another code related to antenna performance that is often set alongside B2462 and B2470 when the shark fin antenna fails due to water intrusion.

Technical Service Bulletins (TSBs) & Recalls

• 17NA214: Addresses OnStar, XM, GPS, or antenna malfunction, which may set DTC B2462, B2470, or B125C, and/or a water leak on the headliner. Recommends replacing the antenna and using a seam sealer (specifically Kent Automotive brand). Also notes water can travel to the A-pillar and cause battery drain issues.
• PIT5362B: An earlier bulletin for 2015 models that addresses inaccurate GPS location and codes B2462, B2470, and B125C. It identified water intrusion as the cause and recommended replacing the antenna with the latest part number. This TSB advised against using sealants, a recommendation that was reversed in the later 17-NA-214 bulletin.

Platform-Specific Known Issues

• The primary issue is a design flaw in the original antenna where the seal fails and a drain hole is misplaced, allowing water to collect inside the housing and corrode the electronics. TSB #17NA214 and #PIT5362B were issued by GM to address this widespread problem on the K2XX platform.

Mechanic-Grade Diagnostic Values

• Voltage from Radio/VCIM to GPS Antenna — expected: 4.0 - 5.5 volts DC. Failure: A reading outside this range suggests a fault in the radio or Telematics module, not the antenna or cable. This is measured at the antenna connector end of the coaxial cable.
• GPS Coaxial Cable Center Conductor Resistance (Continuity) — expected: Less than 5.0 ohms. Failure: Resistance greater than 5.0 ohms indicates an open circuit or break within the cable.
• GPS Coaxial Cable Isolation — expected: Infinite resistance (Open Line). Failure: Any resistance reading less than infinite indicates a short between the center conductor and the outer shield within the cable.

Hidden / Shadow Codes Worth Checking

• B2462-01: Global Positioning System (GPS) Antenna Circuit Short to Battery. The module has detected the signal circuit is shorted to battery voltage. (see via A professional scan tool like the GM GDS2 is required to view these two-digit symptom codes (also called failure bytes).)
• B2462-02: Global Positioning System (GPS) Antenna Circuit Short to Ground. The module has detected the signal circuit is shorted to the vehicle's ground. (see via A professional scan tool like the GM GDS2 is required to view these two-digit symptom codes (also called failure bytes).)
• B2462-04: Global Positioning System (GPS) Antenna Circuit Open. The module has detected a break or high resistance in the signal circuit. This is the most common failure mode from water intrusion. (see via A professional scan tool like the GM GDS2 is required to view these two-digit symptom codes (also called failure bytes).)

Scan Tool Commands That Help

• GM GDS2 (Global Diagnostic System 2): Module Diagnostics -> Telematics Communication Interface Control Module -> Data Display — After replacing the antenna, a technician can use this function to monitor live data from the telematics module, such as satellite count and signal strength, to verify the repair is successful without needing to drive the vehicle.

Wiring & Ground Locations

• Antenna Connectors — Under the headliner, directly attached to the pigtail of the 'shark fin' antenna base.. These are the first connection points to check for water damage or corrosion after lowering the headliner. A bad connection here will cause an open circuit fault.
• K73 Telematics Communication Interface Control Module (VCIM) — Typically located behind the glove box or in the passenger side kick panel area.. The coaxial cable from the roof antenna runs to this module. If the antenna and cable test good, the fault may lie in the connection at this module or the module itself.
• G218 Ground — A common body ground point located in the driver's side A-pillar or kick panel area.. While not a direct cause, this ground is a known weak point on the K2XX platform. A poor connection at G218 can cause a wide range of bizarre, unrelated electrical problems with the BCM and radio, which could complicate diagnosis. Ensuring this ground is clean and tight is a good preventative measure.

Real Owner Repair Stories

• TahoeYukonForum.com user 'e3gordon' (2016 GMC Yukon) — Non-functional navigation.
  ❌ Tried (didn't work) Replacing the roof 'shark fin' antenna., Replacing the Human-Machine Interface (HMI) module.
  ✅ What actually fixed it The dealer installed a new OnStar (VCIM) module. The final resolution was a combination of a bad antenna AND a bad OnStar module. The user noted this fix came from forum knowledge, not from GM technical service recommendations.

When the Usual Fixes Don't Work

• While replacing the 'shark fin' antenna resolves the B2462 code in the vast majority of cases, there are documented instances where this does not complete the repair. In one case, a vehicle owner replaced both the antenna and the HMI module without success. The final fix was the replacement of the OnStar/VCIM module, which had also failed. This indicates that in rare circumstances, the fault can be with the telematics module itself, either independently or as a secondary failure caused by the initial water leak.

OEM Part Supersession History

• 23258463 → 84081919, then 84346803 — The original antenna design was flawed, trapping water. Superseded parts feature a relocated drain hole and improved sealing.
  Heads up: Part numbers are highly specific to vehicle color and options (e.g., 84346803 is for Champagne Silver). Ordering by VIN is critical to ensure a color-matched and functionally correct part.

Model Year Variations Within This Range

• 2015 vs 2018: The official GM repair procedure evolved. The TSB for 2015 models (PIT5362B) advised against using sealant on the new antenna. However, the later TSB for 2015-2018 models (17-NA-214, issued in 2018) explicitly recommends applying a specific automotive seam sealer, indicating a change in GM's long-term repair strategy for this known issue.