Network, generic (extended)

U3569 Anode Multifunction Valve

Check engine lightOn
EmissionsNot relevant
Drive cycleRequired
Limp modePossible

With U3569 the multifunction valve can be driven but does not do what it is told: it stays shut, leaks or reacts too slowly. A solenoid of this kind usually lacks position feedback, so its state is inferred. For an integrated drain and purge valve Hyundai lifts anode pressure a fixed amount over ambient while no current is drawn and the air path is closed, opens the valve and checks after the expected drain time plus a settling period whether pressure has dropped to ambient; if not, the valve counts as stuck closed. GM reads the injector duty instead, which climbs once gas rather than water passes. Stuck shut, the valve lets water flood the anode and nitrogen dilute the hydrogen; stuck open, hydrogen escapes. No public source names U3569. Typical results are a warning, less power or a shutdown.

Likely causes

Valve frozen shut after parking in frost
Valve sticking or leaking from deposits or worn seat
Water level sensor of the separator reads wrong, valve itself fine
Control software needs an update

Symptoms

  • Fuel cell system warning, MIL on
  • Reduced power, uneven fuel cell output
  • Start refused or shutdown, mainly after frost
  • Higher hydrogen consumption

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€300–1,500
Time1–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

anode multifunction valve

Related codes

U3568U356BU356DU3567

References: patents.google.com, patents.google.com, patents.google.com.