U354B

Code

Generic U — Network/User

Hydrogen Tank A Temperature Sensor 2 Circuit

Brand: Generic

Type: U — Network/User

Views: UK: 33 EN: 44 RU: 39

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Page language: EN

Causes

Open or short in sensor wiring (to ground or to battery)
Corroded, loose, or damaged sensor connector/pins
Failed temperature sensor (thermistor or sensor module)
Poor ground or missing reference voltage to the sensor
Water intrusion or mechanical damage at the tank sensor harness
Faulty controller/module reading the sensor (ECU/fuel cell controller)

Symptoms

Malfunction Indicator Lamp (MIL) or hydrogen system warning illuminated
Hydrogen system derate, disable, or reduced availability of hydrogen functions
Incorrect or missing temperature value for Hydrogen Tank A Sensor 2 on scan tool
Stored freeze-frame data showing out-of-range temperature or no signal
Possible inability to perform hydrogen-related diagnostics or readiness

What to check

Read and record U354B and any related codes; note freeze-frame and live data
Verify whether the fault is current or historical and whether it is intermittent
Visually inspect harness and connectors at Hydrogen Tank A and at the controller
Backprobe sensor connector and check for reference voltage and ground presence
Measure sensor resistance/voltage and compare to expected values (sensor spec)
Wiggle harness and connector while monitoring live data for intermittent change

Signal parameters

Signal type: temperature sensor (typically NTC thermistor) producing an analog voltage or resistance proportional to temperature
Typical analog voltage range (typical systems): ~0.1–4.9 V depending on temperature and reference; verify vehicle spec
Typical resistance behavior: resistance decreases with increasing temperature for NTC sensors — compare to sensor chart in service information
Expected temperature operating range: manufacturer-specified (examples: -40 °C to +125 °C); check vehicle spec
Update rate: sensor should update at regular intervals; loss of updates or frozen value indicates a wiring or module issue
Communication note: some systems transmit processed temperature over CAN — verify both raw sensor circuit and CAN data if applicable

Diagnostic algorithm

Retrieve and record all related codes and freeze-frame data. Clear codes and attempt to reproduce the fault to verify persistence.
Visually inspect the hydrogen tank A area, sensor connector, and harness for damage, corrosion, or contamination. Repair any visible issues.
With ignition ON (engine off) or as directed by service manual, backprobe the sensor connector and measure reference voltage and ground continuity at the controller connector.
Measure sensor resistance at the sensor plug (or voltage output) and compare to manufacturer temperature vs resistance chart. Warm or cool the sensor gently (heat gun/submerge in temperature-controlled bath per safety procedures) to confirm response.
Perform continuity checks between the sensor and controller pins to locate opens or shorts; check for short to ground or to battery.
Wiggle test harness while monitoring live data to find intermittent faults. Inspect routing for chafe points and secure harness if needed.
If raw sensor circuit checks OK but scan tool shows invalid data, verify CAN/bus communication to the controller and check for related communication codes (U1000, U0401, etc.).
If wiring and connector tests are good, replace the sensor with a known-good unit and retest. If fault persists after sensor replacement, suspect module/controller fault — consult manufacturer service information before replacing controller.
After repair, clear codes and verify no return of U354B and that hydrogen system operates normally. Document repair and test drive if applicable.