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 U1255: Loss Of Class 2 Serial Data Fault (General): Description
When ignition switch is turned to RUN position, Body Control Module (BCM) receives a vehicle security powertrain status message from Powertrain Control Module (PCM). DTC U1255 will set when BCM does not receive this message within one minute of ignition switch being turned to RUN position. BCM will send message to IPC to come on SECURITY indicator warning light. A current DTC U1255 will change to a history code when BCM receives vehicle security powertrain status message from PCM. If conditions for malfunction no longer exist, history DTC will clear after 100 consecutive ignition cycles. DTC U1255 will also clear when scan tool is used to clear codes.
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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.