Wiring fault in the valve control circuit (open circuit, short to earth or short to supply, chafed or damaged loom); Corroded, loose or damaged connector at the valve or control unit; Faulty anode multifunction valve (solenoid or internal driver fault, or a stuck valve); Low or unstable supply voltage or a poor earth feeding the valve or control unit; Fault inside the controlling module's output driver; Outdated or faulty control unit software, only where the manufacturer has issued a fix for this fault.

U3568

Anode Multifunction Valve Control Circuit.

Generic
Network
Generic code
High severity

How this code is built

U: SystemNetwork
3: Defined bySAE, the same on every car
5: AreaNetwork area 5
68: FaultThe specific fault in that area

What it means

U3568 is listed as 'Anode Multifunction Valve Control Circuit'. The wording points to a fuel cell vehicle, where a control unit manages a valve on the hydrogen (anode) side of the stack. The control unit has seen a fault in the valve's control circuit, such as an open circuit, short circuit or a commanded state that does not match the feedback. U3xxx codes sit in a range that is largely manufacturer-defined, so the exact valve function and set conditions depend on the vehicle and the control unit that reports it.

Symptoms

Fuel cell or powertrain warning light on
Reduced power or the vehicle going into a limited-performance mode
Fuel cell system shutting down or refusing to start or ready
Hydrogen system warning message on the dash
Intermittent fault that returns after clearing

Possible causes

Wiring fault in the valve control circuit (open circuit, short to earth or short to supply, chafed or damaged loom)likely
Corroded, loose or damaged connector at the valve or control unitlikely
Faulty anode multifunction valve (solenoid or internal driver fault, or a stuck valve)possible
Low or unstable supply voltage or a poor earth feeding the valve or control unitpossible
Fault inside the controlling module's output driverrare
Outdated or faulty control unit software, only where the manufacturer has issued a fix for this faultrare

How to diagnose

Read all stored and pending codes and the freeze frame data, noting any other fuel cell, hydrogen or power supply faults and when the fault set.
Check the manufacturer's service information for how this code is set on this model and for the high-voltage and hydrogen safety precautions before any work.
Visually inspect the valve wiring and connectors for chafing, heat damage, water ingress, corrosion and bent or pushed-back pins.
Check the 12 V battery condition and the supply and earth connections to the valve and control unit.
With the system safe and isolated as the manufacturer requires, measure the valve circuit resistance and check for shorts to earth or supply.
Use a bidirectional scan function, if supported, to command the valve and compare the commanded state with the feedback.
Check the valve coil resistance against the manufacturer's specification.
Check for any software update or technical bulletin relating to this fault for the vehicle.

How to fix

Repair or replace damaged wiring and re-pin or replace faulty connectors, sealing them against moisture.
Clean or replace corroded terminals and correct poor earth or supply connections.
Replace the anode multifunction valve if it fails electrical or functional tests, following the manufacturer's procedure for hydrogen system work.
Charge or replace a weak 12 V battery if low voltage is contributing.
Update the control unit software only if the manufacturer lists it as a fix, or replace the module if its output driver is proven faulty.

Can I keep driving?

High severity

Limit driving and have it inspected promptly, because this is part of the hydrogen fuel system and the vehicle may shut down or lose power. Stop and seek assistance if you smell gas, see a hydrogen leak warning, or the vehicle will not run normally.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.