U354E
Hydrogen Tank C Temperature Sensor 1 Circuit.
- Generic
- Network
- Generic code
- Medium severity
How this code is built
- U
- SystemNetwork
- 3
- Defined bySAE, the same on every car
- 5
- AreaNetwork area 5
- 4E
- FaultThe specific fault in that area
What it means
U354E is a generic network and data code relating to the temperature sensor 1 circuit for hydrogen tank C on a hydrogen fuel cell vehicle. A control unit has either lost the signal from this sensor, or received data from it that is missing, implausible or fails its checks. The tank temperature is used to monitor tank condition and manage safe refuelling, so the fault is logged and the system may limit some functions. The exact module that sets the code and the number of tanks vary by model.
Symptoms
- Fuel system or fuel cell warning light on the dashboard
- Hydrogen tank or refuelling warning message
- Reduced power or restricted operation on some models
- Hydrogen level or range reading missing or inaccurate
- Refuelling refused or limited by the vehicle
- Other communication fault codes stored alongside it
Possible causes
- Damaged wiring, poor connection or corrosion at the tank C temperature sensor 1 connectorlikely
- Faulty tank C temperature sensor 1likely
- Open circuit, short circuit or chafed harness between the sensor and the controlling modulepossible
- Network communication fault or data dropout between the module reading the sensor and the module reporting itpossible
- Low or unstable supply voltage or poor earth to the module handling the sensor signalpossible
- Faulty control module or outdated software on it, where the manufacturer lists this as a known cause for the modelrare
How to diagnose
- Read all stored and pending codes with freeze frame data, and note any other network, hydrogen system or tank sensor codes that appear with U354E.
- Check for manufacturer service bulletins or software updates for the model and year relating to tank temperature data.
- Visually inspect the harness and connectors at the tank C sensor and the related control module for damage, water ingress, corrosion or loose pins.
- With live data, check whether the tank C temperature reading is plausible against the other tanks and ambient temperature, and whether it is missing, frozen or jumping.
- Check the supply voltage, earth and network wiring to the module handling the sensor, following the model's wiring diagram.
- Test the sensor circuit for continuity, shorts and resistance against the manufacturer's specification, after the system has been made safe by a trained technician.
- Check the sensor's resistance or output against specification across a temperature range, if the procedure allows.
- Clear the code and road test, then recheck to see whether the fault returns immediately or only under certain conditions.
How to fix
- Repair or replace damaged wiring and clean or replace faulty connectors on the sensor circuit.
- Replace the tank C temperature sensor 1 if it is out of specification, following the manufacturer's procedure.
- Restore any network wiring or module power and earth faults found.
- Update the control module software only if the manufacturer lists an update as a fix for this fault.
- Replace or reprogram a faulty control module only after the wiring and sensor have been fully verified.
Can I keep driving?
Have it checked soon, as the vehicle may restrict refuelling or reduce performance and tank temperature monitoring is a safety function. Stop driving and seek specialist help at once if you smell gas, see a hydrogen leak warning or get a red warning message. Hydrogen and high-voltage work must only be done by trained technicians.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.