U354B code meaning
Hydrogen Tank A Temperature Sensor 2 Circuit
Network system Generic code U35xx codes Check engine light
What U354B means
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.
U354B 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 U354B
- Tank cannot be filled completely
- Hydrogen system warning
Common causes of U354B
- Most likelyWiring or connector fault at the far tank end
- PossibleSecond temperature sensor of tank A failed
- Less likelyEvaluation software misjudging the sensor pair
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
H2 tank a temp sensor 2Sensor wiring
What each part of U354B means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 4B | The exact fault in that area. |
What to do next
- Note U354B 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 U354B
What does U354B mean?
U354B means "Hydrogen Tank A Temperature Sensor 2 Circuit". U354B is the circuit code for the second temperature sensor in tank A. It is a generic code, so it means the same on every make.
Is it safe to drive with U354B?
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 U354B fail an emissions test?
U354B 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 U354B to fix?
Difficulty: workshop only. A typical repair takes 0.3 to 6 hours of work. This is a job for a workshop.
Will U354B clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.