U0100: Lost Communication With ECM/PCM 'A'
What this check-engine code means in plain English, what usually causes it, and what a fix typically costs.
What U0100 means
U0100 means the vehicle's communication network has lost contact with the Engine Control Module (ECM) or Powertrain Control Module (PCM), the computer that manages engine operation. This breaks the chain of communication between critical vehicle systems, often preventing the engine from starting or running correctly.
What causes U0100?
Is U0100 safe to drive?
Driving is generally not recommended with U0100. The vehicle may not start at all, or if it does run, it may stall unexpectedly or operate in a severely limited fail-safe mode. This code indicates a fundamental communication failure with the engine's main computer, which can lead to unpredictable and unsafe vehicle behavior.
U0100 repair cost
Industry-average estimates. Cost depends heavily on the root cause, ranging from a simple fuse replacement to ECM/PCM replacement and reprogramming.
Which one is it for your car?
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