The B1600 code on your 2023 GMC Sierra indicates a malfunction with the ignition key transponder system. This code affects your Sierra's anti-theft system, signaling the vehicle cannot properly communicate with or authenticate the key's transponder chip.
Understanding B1600 on GMC Sierra
Modern keys contain a transponder chip that communicates with the vehicle's immobilizer system. When you insert the key or bring the fob near the vehicle, the immobilizer reads the transponder code. Code B1600 indicates this communication has failed or the code is invalid.
Common Symptoms
- Security or theft deterrent light on
- Engine cranks but won't start
- No crank, no start condition
- Intermittent starting issues
- Key not recognized message
- Vehicle may start with one key but not another
Primary Causes
- Key transponder chip failure
- Key battery low or dead (fob-style keys)
- Damaged key
- Antenna ring around ignition failure
- Body control module communication issue
- Key not properly programmed
- Damaged key fob
Diagnostic Procedure for 2023 Sierra
Try all keys - if one works and another doesn't, the non-working key is likely faulty. Using GM scan tool, access immobilizer/theft deterrent data to see if the key is being recognized. Check key fob battery if applicable. Inspect antenna ring around ignition or start button. Verify key is properly programmed by attempting key relearn procedure.
Repair Solutions
Replace key fob battery if low. If key transponder has failed, a new key must be programmed. Have additional keys programmed to verify system function. Replace antenna ring if it's not reading keys. For intermittent issues, ensure key isn't damaged or has weak transponder. Clear codes after repair and verify consistent starting.