Network, generic (extended)

U354F Hydrogen Tank C Temperature Sensor 2 Circuit

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U354F is set when the circuit of the second temperature sensor in tank C fails. During refuelling the car hands tank data to the station; Toyota describes infrared links between the tank temperature sensors, nozzle and dispenser that set the flow so the gas does not overheat. In a published test series the fill was stopped as soon as either of two tank sensors showed 85 °C, which explains why a missing channel matters: the controller has to fill more cautiously or quit early. FMVSS 308 likewise ties a slower pressure ramp to gas above 85 °C. No maker documents U354F. Expect a hydrogen system warning and refuelling that takes longer or ends short of full, which in turn trims range. The paired sensor is U354E.

Likely causes

Open or short in the wiring of sensor 2 at tank C
Temperature sensor 2 of tank C failed
Evaluation software needing a manufacturer update

Symptoms

  • Refuelling takes longer or stops before full
  • Hydrogen system warning
  • Reduced range after refuelling

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 c temp sensor 2sensor wiring

Related codes

U354EU354BU354D

References: media.toyota.co.uk, hysafejournal.org, law.cornell.edu.