Network, generic (extended)

U3566 Anode Inlet Pressure Sensor 1 Circuit

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

U3566 is set for an electrical fault at anode inlet pressure sensor 1, sitting between hydrogen injector and stack. A GM patent explains why this value is central: it closes the loop for the injector and also feeds anode valve control and the handling of hydrogen in the exhaust. A wrong value derails that loop; in GM's example the injector is held at full duty because a 200 kPa target never shows on a sensor stuck at 100 kPa. GM flags such a sensor when its readings vary by less than 6 kPa over a time window and then runs the anode open loop, about 50 kPa above cathode pressure. Hyundai checks its stack supply pressure sensor against recirculation blower speed and warns in the cluster. As a circuit code U3566 covers opens and shorts; no public source uses it. Expect a warning and reduced power.

Likely causes

Open, short or corrosion in wiring or connector of sensor 1 at the stack
Anode inlet pressure sensor 1 faulty internally
Shared 5 V supply or ground faulty (often with other sensor codes)

Symptoms

  • Fuel cell system warning, MIL on
  • Noticeably reduced power
  • Rough or interrupted fuel cell start

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€150–1,000
Time0.5–3 h

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

Parts involved

anode inlet pressure sensor 1sensor wiring

Related codes

U3567U3564U3576U3568

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