Damaged, corroded or loose wiring or connector at the tank B temperature sensor 2 circuit; Faulty tank B temperature sensor 2 giving an open, shorted or implausible reading; Communication or network fault between the sensor, its module and the hydrogen system control unit; Low or unstable supply voltage or poor earth to the sensor or its module; Fault inside the tank or hydrogen system control unit; Outdated control unit software where the manufacturer has issued a correction for this fault.

U354D

Hydrogen Tank B Temperature Sensor 2 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
4D: FaultThe specific fault in that area

What it means

U354D is a generic code for a fault in the circuit of temperature sensor 2 on hydrogen tank B. The control unit that monitors the hydrogen storage system saw a missing, implausible or out-of-range signal, or lost data from that sensor. Tank temperature is used to manage refuelling and fuel supply safely, so the system may restrict operation until the fault is cleared. The exact tank layout and sensor position depend on the model.

Symptoms

Fuel cell or hydrogen system warning light on the dashboard
Reduced power or limited operation mode
Refuelling refused, restricted or reduced in quantity
Inaccurate or missing hydrogen range or tank readings
Other tank or fuel system codes stored alongside it
Intermittent fault that comes and goes with temperature or vibration

Possible causes

Damaged, corroded or loose wiring or connector at the tank B temperature sensor 2 circuitlikely
Faulty tank B temperature sensor 2 giving an open, shorted or implausible readinglikely
Communication or network fault between the sensor, its module and the hydrogen system control unitpossible
Low or unstable supply voltage or poor earth to the sensor or its modulepossible
Fault inside the tank or hydrogen system control unitrare
Outdated control unit software where the manufacturer has issued a correction for this faultrare

How to diagnose

Confirm the vehicle manufacturer's hydrogen safety procedure and that the technician is trained and equipped to work on high-pressure hydrogen systems before starting.
Read all stored and pending codes and the freeze frame data, noting any other tank, sensor or network codes.
Check for hydrogen system warnings, leak alerts or other related faults, and note whether the fault is current or historic.
Visually inspect the wiring, connectors and mounting around tank B and its sensor for damage, water ingress, chafing or corrosion.
Check the live data for tank B temperatures and compare sensor 2 with the other tank temperature readings for plausibility.
Test the sensor circuit for supply, signal, earth, continuity and shorts, using the manufacturer's wiring diagram and specifications.
Check the related module's supply voltage, earths and network communication.
Check for applicable manufacturer service bulletins or software updates for this model.

How to fix

Repair or replace damaged wiring, terminals or connectors in the sensor circuit.
Replace the tank B temperature sensor 2 if it fails testing, following the manufacturer's procedure for the hydrogen system.
Restore correct power supply and earth connections to the sensor or module.
Repair the network fault or replace the faulty module if testing proves it is at fault.
Update the control unit software only where the manufacturer lists it as a fix for this fault, then clear the code and road test to confirm it does not return.

Can I keep driving?

Medium severity

The vehicle may be driven short distances if it runs normally and shows no hydrogen leak or safety warning, but get it checked soon as refuelling or power may be restricted. Stop driving and seek specialist help if there is any leak warning, smell or other tank fault.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.