Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC B1556: BCM EEPROM Write Error: Notes
DTC B1556 testing is run for each write block of writes to EEPROM. BCM writes to EEPROM cell and then reads data back. DTC B1556 will set when data read by BCM does not match data written to EEPROM after 3 consecutive attempts. DTC B1556 will clear when data read by BCM matches data written to EEPROM or when scan tool is used. A history DTC will clear after 50 consecutive ignition cycles if conditions for fault no longer exist.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.