U3549 indicates a problem with the high‑pressure sensor circuit for the hydrogen tank, meaning the vehicle’s control module is not receiving a proper signal from that sensor.
The sensor inside the hydrogen tank can develop an internal fault, causing it to stop sending a valid signal.
Corroded, damaged, or loose wiring and connectors between the sensor and the control module can interrupt the circuit.
A blown fuse, faulty relay, or loss of reference voltage can prevent the sensor from operating.
The input stage of the PCM that receives the sensor signal may be defective, though this is less common.
No, the PCM is rarely the cause; most often the sensor, wiring, or power supply is at fault.
Yes, but the code will return if the underlying fault remains.
Yes, it relates to the hydrogen system which is monitored for emissions compliance.
Driving with the code may limit hydrogen system operation and should be addressed promptly.