U354F code meaning
Hydrogen Tank C Temperature Sensor 2 Circuit
Network system Generic code U35xx codes Check engine light
What U354F means
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.
U354F at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyWorkshop only
- Typical labor0.3 to 6 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U354F
- Refuelling takes longer or stops before full
- Hydrogen system warning
- Reduced range after refuelling
Common causes of U354F
- Most likelyOpen or short in the wiring of sensor 2 at tank C
- PossibleTemperature sensor 2 of tank C failed
- Less likelyEvaluation software needing a manufacturer update
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
H2 tank c temp sensor 2Sensor wiring
What each part of U354F means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 4F | The exact fault in that area. |
What to do next
- Note U354F and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U354F
What does U354F mean?
U354F means "Hydrogen Tank C Temperature Sensor 2 Circuit". U354F is set when the circuit of the second temperature sensor in tank C fails. It is a generic code, so it means the same on every make.
Is it safe to drive with U354F?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will U354F fail an emissions test?
U354F is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U354F to fix?
Difficulty: workshop only. A typical repair takes 0.3 to 6 hours of work. This is a job for a workshop.
Will U354F clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.