B3055 on 2007-2010 Saturn SKY: No-Start Causes and Immobilizer Fixes

What's Unique About the 2007-2010 Saturn SKY

The Saturn SKY, built on the GM Kappa platform alongside the Pontiac Solstice, uses GM's Passkey III (PK3) transponder-based immobilizer system. These vehicles were also part of the major GM ignition switch recalls. While the recall was for the switch moving out of the 'run' position, any work on the ignition system can sometimes lead to security system communication issues. The most common complaint from owners is an intermittent no-start with a security light, which can often be resolved without replacing parts by using the specific GM 30-minute relearn procedure. The issue is also prevalent on other GM vehicles from the era, such as the Chevrolet Cobalt and HHR.

Diagnostic Flowchart

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

Symptoms You May Notice

• Engine does not crank or turn over
• Engine starts and immediately stalls
• Security warning light is on solid or flashing on the dashboard
• "No Fob Detected" message on the driver information center (if equipped)
• Car fails to start intermittently, but may work after waiting some time

Most Likely Causes

1. Faulty or Damaged Ignition Key 🔴 High Probability → Shop Ignition Switch The transponder chip inside the key head can be damaged from being dropped, getting wet, or from internal failure. The key fob itself can also have failed solder joints, preventing the chip from being energized.
   How to confirm: Try starting the vehicle with a spare key. If the spare key works consistently, the original key is faulty. A scan tool may also show 'Not Present' for the suspect key while showing 'Present' for a good key.
   Typical fix: Replace the faulty key and program the new key 🎬 See how to program a new transponder key yourself. to the vehicle. The OEM key is a 'Circle Plus' B111PT type. In some cases, resoldering the battery contacts inside the fob can fix the issue.
   Est. part cost: $20-$60 for a new key blank, plus programming costs.
2. Loss of Key Synchronization 🟡 Medium Probability This can happen after a battery replacement, if the battery voltage drops too low, after jump-starting, or sometimes for no apparent reason. The BCM/TDM simply loses the learned key code.
   How to confirm: Attempt the manual key relearn procedure. If the procedure completes successfully and the car starts, synchronization was the issue.
   Typical fix: Perform the 30-minute GM Passkey III relearn procedure. 🎬 Watch: Step-by-step guide for the GM 30-minute relearn procedure. This does not require any tools.
   Est. part cost: $0
3. Faulty Immobilizer Exciter Ring/Antenna ⚪ Low Probability This component is a coil around the ignition lock cylinder that energizes the key's transponder chip. It can fail electrically or develop wiring issues, preventing it from powering the key chip.
   How to confirm: A professional scan tool can monitor the data from the Theft Deterrent Module. If the module is powered but receives no signal ('Not Present') with a known-good key, the exciter ring or its wiring is suspect. Resistance checks on the circuit can also pinpoint a failure.
   Typical fix: Replace the immobilizer exciter ring (often part of the ignition lock cylinder assembly) and inspect the wiring harness connecting it to the BCM. The ignition lock cylinder can be sourced under GM part number 20869121.
   Est. part cost: $40-$130 for the lock cylinder assembly.
4. Faulty Body Control Module (BCM) ⚪ Low Probability → Shop Body Control Module The BCM houses the Theft Deterrent Module (TDM) logic on this platform. Like any electronic module, it can fail internally due to voltage spikes, moisture, or age. A GM service bulletin warns that the BCM can be damaged if a ground path is removed while battery power is still connected.
   How to confirm: This is typically a diagnosis of exclusion. If the key, exciter ring, and wiring are all confirmed to be good, but the B3055 code persists, the BCM is the likely culprit. A high-end scan tool is needed to check for internal BCM faults and communication status.
   Typical fix: Replace the Body Control Module. The new module must be programmed to the vehicle with a specialized scan tool like a Tech 2 or equivalent. Some owners on Saturn forums suggest trying to clean the BCM connectors with electrical contact cleaner first.
   Est. part cost: $200-$600 for the part, plus programming.

Rare But Worth Checking

• Radio Frequency Interference (RFI): As noted in GM Technical Service Bulletin PIC5650M, other RFID devices on the keychain can interfere with the signal. This includes other car keys, building access cards, gas station payment fobs, and even some aftermarket phone chargers or LED lights inside the cabin. Before performing complex diagnostics, try starting the car with only the ignition key, removed from all other keys and fobs.
• Flip Key Not Fully Extended: A GM service document notes that if the flip-style ignition key is not fully extended and locked into the straight position, it can cause a misalignment with the exciter ring, leading to a B3055 code. The fix is to simply remove the key, ensure it's fully extended, and re-insert it.

Diagnosis Steps

1. Scan for all DTCs in the Body Control Module (BCM) to confirm B3055 and check for other related codes like B3060 or B3935.
2. Remove all other keys and RFID cards from the keychain. Try starting the vehicle with just the ignition key to rule out RFI as described in TSB PIC5650M.
3. If you have a flip key, ensure it is fully extended and locked straight before inserting it into the ignition.
4. Try the spare key. If the vehicle starts and runs with the spare, the primary key is defective.
5. Inspect the key for any physical damage to the head. The key should be marked with 'PK3' on the shank.
6. Perform the 30-Minute Manual Key Relearn Procedure: a) Turn the key to the 'ON' position (do not start). The security light will illuminate. b) Wait approximately 10-11 minutes until the security light turns off. c) Turn the key 'OFF' for 5-10 seconds. d) Repeat steps a-c two more times for a total of three cycles (about 30 minutes). e) After the third cycle, turn the key off and then attempt to start the engine. The vehicle has now learned the key.
7. If the relearn fails, use a scan tool to monitor the immobilizer data stream from the BCM. Check if the 'Transponder Key' parameter reads 'Present' or 'Not Present'. If 'Not Present' with a known good key, the problem is likely the exciter ring or wiring.
8. Inspect the wiring and connector at the ignition lock cylinder for the immobilizer exciter ring. Check for corrosion or pushed-out pins.
9. If the key is good and wiring is intact but no signal is received, test or replace the exciter ring/ignition lock cylinder assembly (GM Part #20869121).
🎬 Watch this walkthrough for replacing the ignition lock cylinder.
10. If all other components test good, the Body Control Module (BCM) is the likely point of failure and requires replacement and programming by a professional.

Parts You'll Likely Need

• Transponder Ignition Key (OEM #15824471 (or Strattec 5903089)) — The transponder chip in the key is the most common point of failure, either through damage or internal fault. It is a GM B111PT 'Circle Plus' key.
  Trusted brands: ACDelco, Strattec
  OEM price range: $40-$80
  Aftermarket price range: $20-$50
• Ignition Lock Cylinder (OEM #20869121) — This part contains the exciter ring antenna that energizes the key chip. It can fail electrically, preventing communication. It often replaces superceded part numbers like 15918809 and 25848845.
  Trusted brands: GM Genuine Parts, ACDelco
  OEM price range: $42-$130
  Aftermarket price range: $30-$90

Related Codes That Often Appear With This One

• B3060 — This code, 'Unlearned Transponder Key', often appears with B3055, indicating the system sees a key but doesn't recognize its value. This is mentioned in TSB PIC5650M and a related preliminary bulletin PIE0232.
• B3935 — This code relates to 'Transponder Authentication Failed' and is also part of the group of security codes mentioned in TSB PIC5650M.
• B2955 — This code for 'Security Sensor Data Circuit Malfunction' can appear alongside B3055, pointing to an issue in the circuit between the exciter ring and the BCM/TDM.

Technical Service Bulletins (TSBs) & Recalls

• PIC5650M: Notes that an intermittent no crank, no start, or start stall with the security light and DTC B3055 can be caused by Radio Frequency Interference (RFI) from other devices on the key ring or even aftermarket electronics inside the car.
• PIE0232: A preliminary engineering bulletin asking for information on vehicles with B3055, B3060, or B3935, indicating GM was actively investigating the root cause of these immobilizer faults.
• GM Document on Flip Keys: A service document explains that a B3055 can be set if the flip-style key is not fully extended, causing a read error.

Platform-Specific Known Issues

• GM Ignition Switch Recall: → Shop Ignition Switch This vehicle was subject to GM's major ignition switch recall (NHTSA Campaign 14V047000), which could cause the engine to shut off while driving. While not directly causing B3055, issues with the ignition

Mechanic-Grade Diagnostic Values

• Theft Deterrent Module Ground Circuit Resistance — expected: Less than 10 ohms. Failure: A reading greater than 10 ohms indicates an open or high resistance in the ground circuit.
• Theft Deterrent Module B+ Circuit Voltage — expected: Battery Positive Voltage (B+). Failure: Voltage less than B+ indicates an issue in the power supply circuit to the module.
• Immobilizer Signal Circuit Voltage (at BCM) — expected: Less than 1.0 V with ignition ON. Failure: Voltage greater than 1.0 V indicates a short to voltage in the signal wire between the exciter ring and the BCM.
• Immobilizer Signal Circuit Resistance to Ground — expected: Infinite resistance (OL). Failure: Any reading less than infinite indicates a short to ground in the signal wire.
• Immobilizer Signal Circuit End-to-End Resistance — expected: Less than 2.0 ohms. Failure: Resistance greater than 2.0 ohms indicates an open or high resistance in the signal wire itself.

Hidden / Shadow Codes Worth Checking

• B3055 00: The '00' is a GM-specific symptom byte meaning 'No Sub Type Information'. It indicates the base DTC text provides the complete failure description, which is common for this particular code. (see via A GM Tech 2 or equivalent professional scan tool capable of reading GM-specific body codes and symptom bytes.)

Scan Tool Commands That Help

• GM Tech 2: Immobilizer Data Display — Use this function to view live data parameters from the BCM/TDM. Key parameters to watch are 'Transponder Key' (should read 'Present' with a key in the ignition) and 'BCM Key Part Number' to verify the BCM is attempting to read the key.
• GM Tech 2 with TIS2000/SPS2: BCM Programming/Replacement — This function is required after replacing the Body Control Module. The Tech 2, used in either a 'pass-thru' or 'go-between' method with GM's Service Programming System (SPS), is necessary to program the new BCM with the vehicle's correct VIN and security information.
• GM Tech 2: Clear DTCs — After a repair, such as addressing an improperly extended flip key as noted in service information, this function should be used to clear the B3055 from history to verify the fix.

Wiring & Ground Locations

• Body Control Module (BCM) — Located on the right side of the HVAC module, accessible from the passenger footwell area.. The BCM is the central module that contains the Theft Deterrent Module (TDM) logic. All immobilizer signals are processed here. Physical access is needed to test wiring, check connectors, or replace the module.
• G300 — Under the center console.. This is a primary interior ground point. A poor connection at G300 can cause a floating ground for the BCM and other interior modules, leading to a wide range of intermittent electrical issues, including immobilizer faults.
• BCM Connector X4 — One of the main multi-pin connectors on the BCM.. The terminals in this connector are Metra-Pack 280 series. Corrosion or damage to the pins and terminals within this connector that carry power, ground, or the immobilizer signal can directly cause code B3055.
• Theft Deterrent Control Module — On the Saturn SKY, this function is integrated into the BCM, but on some other GM models, it is a separate module located on the top right side of the steering column. For the SKY, all relevant wiring goes to the BCM.. It's important to know that for this specific vehicle, you are diagnosing the BCM, not looking for a separate immobilizer box.

Real Owner Repair Stories

• Reddit user in r/SaturnSky (Saturn Sky Red Line (year not specified), being cross-referenced with a Chevrolet HHR) — A dealership was unable to get a used BCM to work in a different vehicle (HHR) even though the part numbers were compatible.
  ❌ Tried (didn't work) Swapping a used BCM from a Saturn Sky into a Chevrolet HHR., Attempting to reprogram the used, VIN-locked BCM using standard dealer tools.
  ✅ What actually fixed it The discussion confirms that reprogramming a used BCM is difficult even for dealers because it is VIN-locked. While not a direct fix story, it highlights that replacing the BCM with a *used* unit is a significant challenge and often fails, implying a new, programmable BCM is the correct path for a BCM replacement.

OEM Part Supersession History

• Multiple (e.g., 15918809, 25848845) → 20869121 — Part consolidation and design updates over many model years and platforms (Cobalt, HHR, G5, Solstice, Sky).
  Heads up: Part 20869121 is an uncoded ignition lock cylinder. It requires programming and/or special setup procedures using GM service tools after installation to work with the vehicle's existing keys and BCM.