U354C code meaning
Hydrogen Tank B Temperature Sensor 1 Circuit
Network system Generic code U35xx codes Check engine light
What U354C means
U354C flags the circuit of the first temperature sensor in tank B. The maker decides which tank is B, and every series fuel cell car has at least two: the first Mirai carried tanks of 60.0 and 62.4 litres, the Clarity a main and a sub tank. With several tanks the readings can be checked against each other. A Hyundai patent monitors the sensors of three tanks, judges one defective once it sits 20 °C away from the others and replaces its value with a healthy one, so fill control still respects 85 °C and the fuel quantity stays right. Such comparison targets drifting values; an open or shorted sensor as in U354C is recognised directly. No maker documents the code. Sensor 2 of tank B is U354D.
U354C 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 U354C
- Hydrogen system warning
- Refuelling limited or interrupted
Common causes of U354C
- Most likelyOpen or short in the wiring to tank B
- PossibleTemperature sensor 1 of tank B failed
- Less likelyInput stage of the storage control unit faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
H2 tank b temp sensor 1Sensor wiring
What each part of U354C means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 4C | The exact fault in that area. |
What to do next
- Note U354C 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 U354C
What does U354C mean?
U354C means "Hydrogen Tank B Temperature Sensor 1 Circuit". U354C flags the circuit of the first temperature sensor in tank B. It is a generic code, so it means the same on every make.
Is it safe to drive with U354C?
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 U354C fail an emissions test?
U354C 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 U354C to fix?
Difficulty: workshop only. A typical repair takes 0.3 to 6 hours of work. This is a job for a workshop.
Will U354C clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.