U3562 code meaning
Cathode Bypass Valve
Network system Generic code U35xx codes Check engine light
What U3562 means
Unlike U3561, this code concerns how the cathode bypass valve itself behaves: it does not reach or hold the opening the controller asks for, for instance because it sticks. A Toyota patent shows why a valve stuck shut is serious. While a cold stack is warmed by deliberately inefficient generation, bypass air is supposed to thin out hydrogen in the exhaust; if ice holds the valve closed, all of that air enters the stack, which then produces more power than intended. Toyota spots this from compressor outlet pressure above a limit or from stack current straying from its command, then opens the backpressure valve and slows the compressor. A valve stuck open costs stack pressure instead, as Nissan notes. No maker publishes U3562; that stuck air valves switch on the MIL is documented by Toyota for the Mirai (T-SB-0043-23).
U3562 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 4 hours
- Clears after repairAfter a drive cycle
Symptoms of U3562
- Fuel cell system warning, MIL on
- Reduced power or failed start in frost
- Unusual compressor or air noise
Common causes of U3562
- PossibleValve frozen in place after a cold soak
- PossibleValve sticking from deposits or wear
- PossibleActuator too weak or gear damaged
- Less likelyPosition feedback reading wrong, valve itself fine
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Cathode bypass valve
What each part of U3562 means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 62 | The exact fault in that area. |
What to do next
- Note U3562 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 U3562
What does U3562 mean?
U3562 means "Cathode Bypass Valve". Unlike U3561, this code concerns how the cathode bypass valve itself behaves: it does not reach or hold the opening the controller asks for, for instance because it sticks. It is a generic code, so it means the same on every make.
Is it safe to drive with U3562?
Drive gently and only to a workshop. With U3562 the car can go into limp mode (reduced power) to protect itself.
Will U3562 fail an emissions test?
U3562 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 U3562 to fix?
Difficulty: workshop only. A typical repair takes 1 to 4 hours of work. This is a job for a workshop.
Will U3562 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.