The C0549 code indicates that the control module has detected an open circuit in the vacuum sensor system. This means the electrical path is broken, preventing the sensor from sending a voltage signal to the computer.
The sensor has suffered an internal electrical failure, creating an open circuit within the component.
Wires leading to the sensor are broken, frayed, or severed due to heat, vibration, or external damage.
Oxidation or loose pins at the sensor plug prevent a complete electrical connection.
A fuse providing power to the vacuum sensor circuit has blown, opening the circuit.
An internal failure in the PCM/ECM circuit processing the sensor signal, though this is rare.
No. This code is specifically for an electrical open circuit. A physical vacuum leak would typically trigger a different code related to sensor range or performance.
No. It is highly uncommon for the PCM to be the cause of C0549; the issue is almost always located at the sensor or within the wiring harness.
The vehicle will usually remain drivable, but specific vacuum-dependent features may malfunction or enter a fail-safe mode.