B3055 on 2012-2016 GMC Yukon Denali: Key Not Detected, No Start Causes and Fixes

What's Unique About the 2012-2016 Gmc YUKON DENALI

The 2012-2016 Yukon Denali spans two vehicle generations with different key systems, which affects the diagnosis of B3055. The 2012-2014 (GMT900) models often use a flip key that can cause this code if not fully extended straight when inserted into the ignition, a well-documented issue in GM TSB PIT5030E. The 2015-2016 (K2UG) models use a more modern key fob, sometimes with a push-button start, where issues can stem from the fob itself, the keyless entry antennas, or radio frequency interference (RFI) from aftermarket devices like phone chargers or LED lights, as noted in TSB PIC5650.

Diagnostic Flowchart

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

Generation note: The 2012-2016 range covers two generations: the third (GMT900, 2012-2014) and the fourth (K2UG, 2015-2016). While the code's meaning is the same, a common cause on 2012-2014 models is an improperly extended flip key. The 2015-2016 models have a different key and ignition design, so causes are more likely a faulty key fob, immobilizer antenna, or RFI.

Symptoms You May Notice

• Engine will not crank or start.
• Engine starts briefly and then immediately stalls.
• Security indicator light is illuminated or flashing on the dashboard.
• "Service Theft Deterrent System" or "Theft Attempted" message appears on the driver information center (DIC).
• On keyless start models, a "No Fob Detected" message may appear.

Most Likely Causes

1. Defective or Damaged Ignition Key 🔴 High Probability The transponder chip inside the key is passive and durable but can be damaged from being dropped, water exposure, or internal failure. A broken key housing can also cause issues.
   How to confirm: The simplest test is to try starting the vehicle with a spare key. If the spare key works, the original key is faulty. A technician can also use a scan tool to see if the 'Transponder Key' parameter reads 'Present' for each key.
   Typical fix: Replace the faulty key. A new key must be cut and programmed to the vehicle by a dealer or an automotive locksmith. 🎬 Watch: How to program a new GM key yourself for free.
   Est. part cost: $75-$250
2. Incorrect Key Usage (2012-2014 Flip Keys) 🟡 Medium Probability A widely known issue covered by GM Technical Service Bulletin (PIT5030E) notes that if the flip key is not fully extended and locked straight, its angle can prevent the immobilizer from reading the transponder chip.
   How to confirm: Remove the key, ensure it is fully extended and locked straight, then re-insert it and attempt to start the engine. If it starts consistently in the correct position, this is the cause.
   Typical fix: No parts needed. This is a user-operation issue. Ensure the key is always fully extended before use. The TSB advises dealers to share this information with the customer.
   Est. part cost: $0
3. Faulty Immobilizer Antenna/Exciter Coil 🟡 Medium Probability This coil, which surrounds the ignition lock cylinder (on keyed models) or is in the center console (on push-button models), energizes the key's transponder. It can fail over time, preventing it from powering the key chip.
   How to confirm: A technician can use a scan tool to monitor immobilizer data. If no key data is ever received with multiple known-good keys, the antenna is suspect. The circuit can also be tested for proper resistance and voltage.
   Typical fix: Replace the immobilizer antenna ring. On keyed models, this is around the ignition switch. On push-button start models, it may be located in the center console transmitter pocket.
   Est. part cost: $50-$150
4. Radio Frequency Interference (RFI) ⚪ Low Probability As detailed in GM TSB PIC5650K, aftermarket electronics like phone chargers, USB power banks, and especially LED lighting can emit RFI that 'jams' the 125 kHz signal between the key and the car. Even having other vehicle keys or building access cards on the same keychain can cause interference.
   How to confirm: Remove all other keys and access cards from the key ring. Unplug all aftermarket devices (phone chargers, dash cams, etc.) from the 12V and USB ports. If the vehicle starts reliably after this, one of the removed items was the cause.
   Typical fix: Identify and remove the source of the RFI. Do not use low-quality aftermarket chargers or LED bulbs. Keep other transponder keys separate.
   Est. part cost: $0
5. Dead or Weak Key Fob Battery ⚪ Low Probability While the transponder chip is typically passive (powered by the car's antenna), on systems with keyless start (2015-2016 models), a weak fob battery can cause communication issues with the vehicle's security system.
   How to confirm: Try placing the key fob in the designated transmitter pocket (often in the center console or glove box) as described in the owner's manual, which allows the car to start even with a dead fob battery. 🎬 See how to bypass the 'No Remote Detected' message. If it starts, the fob battery is the issue.
   Typical fix: Replace the CR2032 battery inside the key fob.
   Est. part cost: $5-$10

Rare But Worth Checking

• Body Control Module (BCM) Failure: Although rare, the BCM itself can fail. This is usually the last part to suspect after all other components (keys, antenna, wiring) have been checked and confirmed to be working. A BCM failure will often be accompanied by other strange electrical issues. Diagnosis requires a high-end scan tool to verify the BCM is unresponsive or malfunctioning.
• Wiring Harness Damage: Damage to the wiring between the immobilizer antenna and the BCM can cause an open or short, leading to this code. This might occur from previous dash repairs or chafing over time. A technician would test the circuit for continuity, shorts to ground, or shorts to voltage.

Diagnosis Steps

1. Try the spare key. This is the easiest and fastest way to rule out a single faulty key.
2. For 2012-2014 models, ensure the flip key is fully extended and locked straight before inserting it into the ignition. Try it multiple times to confirm.
3. Remove any other transponder keys, access cards, or toll passes from the keychain. Unplug all aftermarket 12V or USB devices (chargers, dashcams, etc.) to eliminate Radio Frequency Interference (RFI).
4. For 2015-2016 models with push-button start, if a 'No Fob Detected' message appears, try placing the key fob in the transmitter pocket as specified in the owner's manual to rule out a dead fob battery.
5. Visually inspect the key for any physical damage, such as a cracked case or water damage.
6. Use a professional scan tool to read the status of the immobilizer system in the BCM. Check if the 'Transponder Key' data PID shows 'Present' when a key is in the ignition.
7. If multiple keys fail and RFI is ruled out, inspect the wiring and connector at the immobilizer antenna (exciter coil) for damage.
8. If all other components are verified as good, the Body Control Module (BCM) may be at fault and requires professional diagnosis and likely replacement/programming.

Parts You'll Likely Need

• Ignition Key / Key Fob — The transponder chip in the key is the most common point of failure. If the spare key works, the original key is bad.
  Trusted brands: ACDelco, GM Genuine Parts
  OEM price range: $100-$250
  Aftermarket price range: $50-$150
• Immobilizer Antenna / Transponder Coil — This coil powers the key's transponder chip and reads its signal. It can fail, preventing communication even with a good key.
  Trusted brands: ACDelco, Dorman
  OEM price range: $70-$150
  Aftermarket price range: $40-$90

Related Codes That Often Appear With This One

• B3060 — This code often relates to a failure in the transponder sensor circuit, pointing towards the same set of problems as B3055. It is frequently listed alongside B3055 in GM service bulletins.
• B3935 — This code indicates a transponder authentication failure, meaning a signal was received but was incorrect. It can appear alongside B3055 if the key signal is intermittent or corrupt.
• B2955 — This code points to a malfunction in the security sensor data circuit, which is part of the same immobilizer system.

Technical Service Bulletins (TSBs) & Recalls

• PIT5030E: Addresses intermittent no-crank on 2012-2014 models caused by the flip key not being fully extended.
• PIC5650 (versions M, K, G, B): A comprehensive diagnostic tip for intermittent no-start, security lights, and related codes like B3055. It heavily emphasizes checking for Radio Frequency Interference (RFI) from aftermarket devices.

Platform-Specific Known Issues

• An intermittent no-crank or start-and-stall condition is documented in GM TSB PIC5650M for vehicles including the 2016 Yukon Denali, which lists B3055 as a potential code and points heavily towards RFI as a hard-to-duplicate cause.
• For 2012-2014 models, GM TSB PIT5030E specifically calls out that an incompletely extended flip key can cause a no-crank/no-start and set a history code B3055.
• For 2015-2016 models with keyless start, TSB PIC5650 series notes that a 'No Fob Detected' message can be a symptom of this issue, but the vehicle should still start if the fob is placed in the transmitter pocket.

Mechanic-Grade Diagnostic Values

• Theft deterrent module ground circuit resistance — expected: Less than 10 ohms. Failure: A value greater than 10 ohms indicates an open or high resistance in the ground circuit.
• Theft deterrent module B+ circuit voltage — expected: Battery Positive (B+) Voltage. Failure: Less than B+ indicates an open or high resistance in the power feed circuit.
• Immobilizer signal circuit voltage to ground (Ignition ON) — expected: Less than 1 V. Failure: A value greater than 1 V indicates a short to voltage in the signal circuit between the immobilizer module and the BCM.
• Immobilizer signal circuit resistance to ground (Ignition OFF) — expected: Infinite resistance (OL). Failure: A value less than infinite indicates a short to ground in the signal circuit.
• Immobilizer signal circuit end-to-end resistance — expected: Less than 2 ohms. Failure: A value greater than 2 ohms indicates an open or high resistance in the signal circuit itself.

Hidden / Shadow Codes Worth Checking

• B3055 00: The '00' symptom byte indicates 'No Sub Type Information', meaning the primary code description is considered complete and no further detail is provided by a sub-code. (see via Professional scan tools like GM GDS2/Tech2 may display the symptom byte.)

Scan Tool Commands That Help

• GM GDS2 / Tech2, Autel, Topdon, Auto Pro Pad: Immobilizer Learn / Security Learn / Add Key — This function is required after replacing an ignition key or the Body Control Module (BCM) to program the new component's unique transponder ID into the vehicle's security system. The automated process typically takes about 10-12 minutes.
• GM GDS2 / Tech2: Immobilizer Data Display — Used during diagnosis to view live data PIDs such as 'Transponder Key Status' or 'Environment Identification'. This helps confirm if the BCM is detecting a key at all, or if it's detecting an invalid key, which helps differentiate a bad key from a bad antenna.
• Manual Procedure (No Tool): 30-Minute Relearn Procedure — Used to program the first key when all keys are lost or when replacing the BCM without access to a proprietary scan tool. It involves cycling the ignition on for three consecutive 10-minute intervals.

Wiring & Ground Locations

• Body Control Module (BCM) — On both GMT900 (2012-14) and K2UG (2015-16) platforms, the BCM is located inside the cabin on the driver's side, behind the lower dashboard panel, to the left of the steering column and near the interior fuse block.. The BCM is the central module for the Passkey III immobilizer system. All wiring from the immobilizer antenna is routed to the BCM, and it makes the final decision to enable or disable the engine start.
• BCM Ground — A critical ground for the BCM is located inside the cab, near the front left speaker. Access requires removing the driver's side A-pillar trim cover and pulling up the front dash trim piece.. A poor ground connection at this location can cause intermittent BCM malfunction, leading to erratic behavior of the security system and potentially setting a B3055 code even if all components are good.
• BCM Connector X1, Pin E — This is a specific pin on one of the main connectors at the Body Control Module.. This is the signal circuit from the theft deterrent module/antenna. Technicians use this pin as a test point for checking voltage and resistance to diagnose shorts or opens in the wiring harness.

Real Owner Repair Stories

• YouTube channel 'Hands On Auto Training' (2015 Chevrolet Malibu (similar GM immobilizer system)) — No crank, no start, security light on, code B3055 was current and would return immediately after clearing.
  ❌ Tried (didn't work) Clearing the DTCs (code returned instantly).
  ✅ What actually fixed it The transponder chip inside the original key had failed. The technician confirmed the scan tool read 'no key detected'. Programming a new key to the vehicle resolved the no-start condition.
• YouTube channel 'ADD AUTOMOBILE SERVICES' (2013 Chevrolet Equinox (similar GM immobilizer system)) — Intermittent no start with security light staying on. Code B3055 was present.
  ❌ Tried (didn't work) Cycling the key multiple times sometimes worked, but the problem was recurring.
  ✅ What actually fixed it The transponder in the original key was failing intermittently. The technician used a VVDI key tool to read the data from the faulty key and clone it onto a new 'super chip'. He then placed this new chip inside the original key fob, which provided a reliable signal and permanently fixed the intermittent no-start.

"I Checked Everything" — The Actual Cause

• The system can test perfectly (good key, good antenna, good BCM) but still set B3055 due to Radio Frequency Interference (RFI) from low-quality aftermarket devices like phone chargers or LED lights jamming the 125 kHz key signal. The fix is to unplug all devices and test again, as documented in TSB PIC5650.
• On 2012-2014 models with a flip key, the vehicle may intermittently fail to start and set a history code for B3055 if the key is not fully extended and locked in the straight position when inserted into the ignition. All components will test as good because the issue is operational. This is documented in TSB PIT5030E.

Model Year Variations Within This Range

• 2015-2016 (K2UG with Push-Button Start): The procedure for adding a new key when one working key is present is different. It does not require a scan tool or a 30-minute wait. The procedure involves turning the mechanical key in the driver's door lock 5 times, placing the new fob in the console pocket, and pressing the start button.
• 2012-2014 (GMT900 with Flip Key): These models are uniquely susceptible to no-starts caused by the flip key not being fully extended, which changes the angle of the transponder relative to the antenna coil in the ignition cylinder. This issue does not apply to the 2015+ models with a different key design.