U0151 on 2015-2019 GMC Sierra Denali: Lost Communication With Airbag Module Causes & Fixes

What's Unique About the 2015-2019 Gmc SIERRA DENALI

For the 2015-2019 K2XX platform Sierra, this code is frequently linked to specific, documented issues. One is a pinched dash harness located between the instrument panel's left mounting bracket and the truck's body, a known issue that can cause a variety of electrical problems, including this code. Another common source is a logic lock-up or internal failure of the Serial Data Gateway Module (SDGM), which acts as the central router for all vehicle network traffic. These platform-specific issues are often the root cause, rather than a simple failure of the airbag module itself.

Diagnostic Flowchart

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

Generation note: The 2015-2018 models and the 2019 'Limited' model are on the K2XX platform. The all-new 2019 model is on the T1XX platform. The most relevant Technical Service Bulletins (TSBs) for this code apply specifically to the K2XX platform trucks.

Symptoms You May Notice

• Airbag warning light is on continuously
• "Service Airbag System" or "Service Safety Restraint System" message on the Driver Information Center (DIC)
• Inability for a scan tool to communicate with the 'SIR' or 'RCM' module.
• In some cases, other seemingly unrelated electrical issues may be present if the cause is a network-wide problem (e.g., radio issues, fluctuating gauges, no-start, Service Stabilitrak message).

Most Likely Causes

1. Pinched Dash Wiring Harness 🔴 High Probability A known issue documented in GM Technical Service Bulletin #PIT5288H. The harness can get trapped between the left instrument panel mounting bracket and the body, near the parking brake pedal assembly.
   How to confirm: With the driver's side dash access panel removed, visually and physically inspect the main harness for any signs of being pinched, chafed, or damaged where it passes the metal dash support structure. The TSB notes that the harness should be able to move freely; if it's tight against the bracket, it's likely pinched.
   Typical fix: Loosen the bracket, free the harness, and carefully open the loom to inspect and repair any damaged wires. The harness should then be properly rerouted, sometimes with a new zip tie, to prevent future damage.
   Est. part cost: $0-$25 for wire repair supplies
2. Serial Data Gateway Module (SDGM) Fault 🟡 Medium Probability GM TSB #20-NA-212 (which supersedes #PIT5586E) identifies that the SDGM can enter a 'logic lock' state or suffer from poor pin connections, causing widespread communication loss.
   How to confirm: This typically requires a dealer-level scan tool to check for multiple 'U' codes and to attempt communication with the SDGM. A technician will inspect the X1 and X2 connectors at the SDGM for bent, loose, or backed-out terminals.
   Typical fix: For a 'logic lock', a 'hard reset' by disconnecting the SDM fuse (often F40 or F45 in the underhood block) for 30+ seconds can resolve the issue. If that fails, the SDGM may need reprogramming with updated software. In cases of hardware failure or pin damage, the module or its connector terminals must be replaced.
   Est. part cost: $60-$300 for a new SDGM
3. Corroded/Blown Fuse or Fuse Block Connection 🟡 Medium Probability The underhood fuse block is susceptible to moisture intrusion, which can cause corrosion on the fuse terminals for the SDM, leading to high resistance or a blown fuse.
   How to confirm: Visually inspect the SDM/Airbag fuses in the underhood fuse block (often labeled 'SIR' or 'Airbag', check fuses 40 and 45). Look for white or green corrosion on the fuse legs or in the terminal slots. Test for power on both sides of the fuse with a test light or multimeter.
   Typical fix: Replace the blown or corroded fuse. If the terminals in the fuse block are heavily corroded, they must be cleaned with a terminal cleaning tool or electrical contact cleaner. In severe cases, the entire fuse block may need replacement.
   Est. part cost: $1-$20 for fuses and cleaner
4. Poor Power or Ground to SDM ⚪ Low Probability General electrical issues like corrosion or loose connections can affect any module. TSB 18-NA-161 points to a poor body ground at G218 as a cause for various electrical issues.
   How to confirm: Using a multimeter, check for 12V power and good ground continuity at the Sensing and Diagnostic Module (SDM) connector, following a vehicle-specific wiring diagram. The SDM is typically under one of the front seats.
   Typical fix: Clean or repair the faulty power or ground circuit. This could involve cleaning a ground point on the chassis (like G218) or repairing a broken wire.
   Est. part cost: $0-$25
5. Failed Sensing and Diagnostic Module (SDM) ⚪ Low Probability While possible, the SDM itself is less likely to fail than the wiring or gateway module. However, bulletin 15796 notes some 2016 models had SDMs with hairline cracks in the mounting feet, potentially affecting function.
   How to confirm: This is a process of elimination. If all fuses, wiring, power, grounds, and the SDGM have been confirmed to be good, the SDM itself is the likely culprit.
   Typical fix: Replace the SDM. The new module must be programmed to the vehicle's VIN using a specialized scan tool.
   Est. part cost: $300-$600 for a new SDM

Rare But Worth Checking

• Low Battery Voltage: Extremely low battery voltage during startup can cause temporary communication glitches between modules. TSB #PIT5288H mentions a dead battery as a possible related symptom. If the code appeared after a jump-start or with a weak battery, charge and test the battery and check battery cable connections for tightness and corrosion first.

Diagnosis Steps

1. Perform a full vehicle scan to check for DTCs in all modules. Note if U0151 is isolated or if many other 'U' codes are present.
2. Check the SDM/Airbag related fuses (e.g., F40, F45) in the underhood fuse block for power on both sides and for any signs of corrosion.
3. If many communication codes are present, suspect a network-wide issue. Focus on TSB #20-NA-212. Try removing the SDM fuse for over 30 seconds to reset the module. If that fails, inspect the Serial Data Gateway Module (SDGM) and its connectors for damage.
4. If U0151 is the primary code, focus on TSB #PIT5288H. Remove the driver's side dash end cap and inspect the wiring harness for pinching near the metal support bracket by the parking brake assembly.
5. Check for stable battery voltage (12.4V+). Ensure the battery is fully charged and that the positive and negative cable clamps are tight and clean.
6. If wiring and the SDGM appear okay, locate the Sensing and Diagnostic Module (SDM) under the driver or passenger seat. Inspect the wiring and connector directly at the module for power, ground, and any signs of damage or corrosion from moisture.
7. If all wiring and other modules are confirmed good, the SDM itself is the likely point of failure and may require replacement and programming.

Parts You'll Likely Need

• Serial Data Gateway Module (SDGM) (OEM #13599318, 13542838) — This module can suffer from software glitches or hardware failure, causing a network shutdown that logs U0151 and other codes, as noted in TSB #20-NA-212.
  Trusted brands: ACDelco, GM Genuine Parts
  OEM price range: $70-$150
  Aftermarket price range: $50-$120
• Sensing and Diagnostic Module (SDM) (OEM #13518051, 13518054) — If all wiring and network modules are functioning correctly, the SDM itself may have failed internally, preventing it from communicating. Part number depends on whether the vehicle has roof airbags.
  Trusted brands: ACDelco, GM Genuine Parts
  OEM price range: $300-$600
  Aftermarket price range: $250-$500

Related Codes That Often Appear With This One

• U0100 — Lost Communication with ECM. Often appears with U0151 when the Serial Data Gateway Module (SDGM) is the root cause.
• U0140 — Lost Communication with Body Control Module. Also points towards a network-wide issue originating from the SDGM or a major wiring problem.
• U0126 — Lost Communication With Steering Angle Sensor Module. This code is listed in TSB #PIT5288H as a potential companion code when the dash harness is pinched.
• U0073 — Control Module Communication Bus 'A' Off. This is a general code indicating the entire high-speed data bus is down, often caused by the SDGM or a wiring short.
• U0155 — Lost Communication With Instrument Panel Cluster (IPC) Control Module. This code is also listed in TSBs related to SDGM and wiring faults.

Technical Service Bulletins (TSBs) & Recalls

• PIT5586E / 20-NA-212: Details issues with the Serial Data Gateway Module (SDGM) causing multiple communication codes, including U0151.
• PIT5288H: Points to a pinched wire harness in the left instrument panel area as a cause for U0151 and other electrical problems.
• 18179: A recall that provides a diagnostic step for U0151 (pulling the SDM fuse) when encountered during service.

Platform-Specific Known Issues

• TSB #PIT5288H: Documents a condition where the dash harness can be pinched by the left instrument panel mounting bracket, causing shorts that lead to U0151 and a host of other electrical DTCs and symptoms.
• TSB #20-NA-212 (supersedes #PIT5586E): Describes a fault where the Serial Data Gateway Module (SDGM) can stop communicating due to a software 'logic lock' or bad connector pins, leading to multiple 'U' codes, including U0151. The fix is often reprogramming the module or repairing the terminals.
• Recall #18179: While for a different vehicle (GMC Terrain), this recall for an SDM communication fault instructs technicians to pull the SDM fuse for 30+ seconds if U0151 is present before attempting to reprogram, confirming this as a valid reset procedure.

Mechanic-Grade Diagnostic Values

• CAN Bus Network Resistance — expected: Approximately 60 Ohms (± 5 Ohms). Failure: A reading of ~120 Ohms indicates one of the two terminating resistors (often in the SDGM or another module) is offline. An open circuit (OL) or 0 Ohms indicates a wiring short or break.
• CAN High Voltage (Pin 6 at DLC) — expected: ~2.7 Volts (Key On, Engine Off). Failure: No voltage or voltage significantly different from the expected value can indicate a short or open on the CAN High wire.
• CAN Low Voltage (Pin 14 at DLC) — expected: ~2.3 Volts (Key On, Engine Off). Failure: No voltage or voltage significantly different from the expected value can indicate a short or open on the CAN Low wire.
• SDM Power Supply — expected: 12.0 ± 0.5 V. Failure: Low or no voltage indicates a problem with the power feed circuit or fuse.
• SDM Ground Continuity — expected: Less than 0.1 Ω. Failure: High resistance indicates a poor ground connection, which can cause the module to malfunction.

Scan Tool Commands That Help

• GDS2 / High-End Aftermarket (e.g., Autel): SDM Primary Key Reset — This function may be required after replacing or reprogramming the Sensing and Diagnostic Module (SDM) to re-establish communication and security keys with other vehicle modules.
• GDS2 / High-End Aftermarket: Clear Crash Data — After a collision where airbags have deployed, the SDM will store 'crash data' and set hard codes (like B0051) that cannot be cleared with a standard 'Clear DTCs' command. This special function is required to make the module operational again, though many shops opt to send the module out for this service.

Wiring & Ground Locations

• G218 — Under the driver's side of the instrument panel, near the A-pillar, behind the trim. It is a ground stud on the body.. This is a major ground point for the Body Control Module (BCM) and other interior electronics. TSB PIT5405C identifies a poor connection here (often due to the dash insulator mat getting trapped under the ground nut) as a cause for numerous communication DTCs, including those often seen with U0151.
• Sensing and Diagnostic Module (SDM) — Bolted to the floor, typically under the driver's or front passenger's seat, beneath the carpet.. This is the module that has lost communication. All power, ground, and communication wires terminate here. Physical inspection for corrosion from water intrusion (wet carpets) or connector damage is crucial.
• Serial Data Gateway Module (SDGM) — Typically located behind the instrument panel, often to the left of the steering column.. This module is the central hub for CAN bus communication. The SDM communicates through the SDGM. A fault in the SDGM or its connectors (X1, X2) can isolate the SDM from the rest of the network.
• DLC (Data Link Connector) Pins — Under the driver's side dashboard.. Pin 6 (CAN High) and Pin 14 (CAN Low) are the direct access points for testing the high-speed communication bus that the SDM uses. Technicians use these pins to measure network resistance and voltage.

Real Owner Repair Stories

• Reddit user @thomassowellistheman (2015+ Silverado (Implied)) — "Service Air Bag" message on dash. Scan tool was unable to communicate with the Restraints Control Module and showed active code U0151 in the Instrument Panel Cluster and Vehicle Communication Interface Module.
  ❌ Tried (didn't work) Initial scan for specific SRS codes (failed due to no communication).
  ✅ What actually fixed it The user located and replaced a blown fuse for the SRS system. After replacement, the airbag light went off and communication was restored.

OEM Part Supersession History

• 13509768, 13524297, 13524298, 13599317 → 13599318 — GM regularly updates service parts to integrate new materials, technologies, or fix previously identified issues.
  Heads up: The replacement part 13599318 requires programming and/or special setup procedures with GM-level software (GDS2) to function correctly in the vehicle.