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U354B Hydrogen Tank A Temperature Sensor 2 Circuit

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U354B is the circuit code for the second temperature sensor in tank A. One probe cannot capture a long tank during a fast fill: in tests published in the HySafe journal, sensors in on-tank valves at both ends of a Type IV tank finished a fill around 30 °C apart, and the authors concluded that even two positions miss the hottest zone. A second sensor thus gives the controller a cross-check and a second view of the gas. Honda's 2019 dealer notice for the Clarity Fuel Cell describes the flip side: a false reading between two tank sensors kept the tank from being filled completely. No maker documents U354B publicly. With sensor 2 lost, expect a warning and cautious, perhaps incomplete fills; sensor 1 of the same tank is U354A.

Likely causes

Wiring or connector fault at the far tank end
Second temperature sensor of tank A failed
Evaluation software misjudging the sensor pair

Symptoms

  • Tank cannot be filled completely
  • Hydrogen system warning

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€50–4,000
Time0.3–6 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

h2 tank a temp sensor 2sensor wiring

Related codes

U354AU354DU354F

References: hysafejournal.org, static.nhtsa.gov.