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DTC codes / U35xx · Network communication / U3567

U3567Anode Inlet Pressure Sensor 2 Circuit

U3567 indicates that the powertrain control module has detected an abnormal condition in the electrical circuit for the anode inlet pressure sensor 2, which is used on fuel cell or alternative fuel vehicles to monitor hydrogen pressure at the anode inlet. The computer compares the sensor signal voltage against expected values and sets this code when the signal is out of range, erratic, or missing entirely.

SystemNetwork
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaNetwork communication

Symptoms you may notice

  • Illumination of the malfunction indicator lamp (MIL) on the dashboard, often with no other noticeable symptoms.
  • Reduced power output or a limp-home mode if the fault affects fuel cell stack protection strategies.
  • Rough running or hesitation during acceleration if the pressure reading is used for fuel delivery calculations.
  • Inability to start or sudden shutdown if the system interprets the pressure signal as unsafe.
  • A message on the driver information display warning of a fuel cell system fault or reduced performance.

Common causes, most likely first

  1. Faulty anode inlet pressure sensor 2, such as an internal short or open circuit in the sensing element.
  2. Damaged or corroded wiring harness between the sensor and the control module, including chafed wires or broken connectors.
  3. Loose, corroded, or water-intruded electrical connector at the sensor or at the control module.
  4. Failed pressure regulator or blockage causing actual pressure to fall outside the sensor's expected range, which the module may interpret as a circuit fault.
  5. Contamination or moisture in the anode inlet pressure sensor 2, leading to an erratic signal.
  6. Internal fault in the powertrain control module or fuel cell control module affecting the sensor reference voltage or signal return.

How to diagnose and fix it

  1. Connect a scan tool and record all stored codes and freeze-frame data to confirm U3567 is the primary fault and not a secondary code.
  2. Visually inspect the anode inlet pressure sensor 2 and its connector for damage, corrosion, or loose pins, and repair as needed.
  3. Check the sensor's reference voltage and ground at the connector with a digital multimeter; compare to manufacturer specifications.
  4. Back-probe the signal wire and monitor the voltage while gently wiggling the harness to detect intermittent faults.
  5. Test the sensor's resistance or voltage output with a known pressure source if the manufacturer provides a procedure, and replace the sensor if it is out of specification.
  6. Inspect the entire circuit for shorts to ground or power, and repair any damaged wiring before replacing the sensor.
  7. Clear the codes and perform a road test to verify the repair, ensuring the monitor runs and the MIL stays off.

Anode pressure sensor circuit pitfalls

  • A common misdiagnosis is replacing the anode inlet pressure sensor 2 when the actual problem is a corroded connector pin or a chafed wire that only acts up under vibration.
  • The code can be set by a genuine mechanical pressure problem, such as a stuck regulator or a blocked filter, because the control module may not distinguish between an electrical fault and an out-of-range pressure signal.
  • On some fuel cell vehicles, a low 12-volt battery or poor ground can cause a reference voltage drop that mimics a sensor failure, so always verify battery and ground integrity first.
  • U3567 is often accompanied by other pressure sensor or fuel cell system codes, and diagnosing it in isolation without checking related codes can lead to an incomplete repair.
  • The sensor may test fine at room temperature but fail when exposed to operating heat, so a hot-soak test or live data monitoring during a test drive is essential.

Can I keep driving with U3567?

If the only symptom is the warning light and the vehicle drives normally, you may drive cautiously to a repair shop, but avoid hard acceleration or long trips. If the vehicle enters limp mode, shuts down, or displays a safety warning, stop driving and have it towed to prevent damage to the fuel cell system.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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