U3013 indicates that the powertrain or body control module has detected an open circuit on the input power supply labeled “C”. In practical terms, the module is not receiving the expected voltage on that specific power feed, which can affect its ability to operate and communicate on the network.
A missing or failed fuse is the most common reason the power feed becomes open.
Broken, chafed, or corroded wires can interrupt the power path, causing an open circuit.
If the relay that supplies power to the circuit does not close or the ignition switch is worn, voltage will not reach the module.
A weak or missing ground can mimic an open power condition in the module’s diagnostics.
The module itself can develop an internal fault that prevents it from recognizing the power input, though this is less common.
Only in very rare cases does the PCM itself cause a false U3013; it should be considered after all other hardware is verified.
No. The PCM itself is rarely the cause of U3013. The problem is usually upstream (fuse, wiring, relay, or the control module that sets the code). Only after verifying all those components should a PCM be considered, and even then it is an uncommon fix.
Yes. A missing or failed fuse on the power circuit that feeds the module will create an open condition, which sets U3013. Checking the fuses should be the first step.
The vehicle may still run, but you may experience loss of certain functions (e.g., power windows, instrument cluster) and potential stalling. It is advisable to diagnose and repair the issue promptly to avoid being stranded.
Intermittent opens are often caused by loose connectors, corroded pins, or a failing relay that heats up and drops out. A thorough inspection of the harness and connectors usually reveals the culprit.