U355EExpander Inlet Pressure Sensor 2 Circuit
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- U355E names a circuit fault on pressure sensor 2 at the expander inlet. Conditions there are harsh: cathode exhaust carries the product water of the stack, and Volkswagen notes in a turbine patent that the pressure drop inside the turbine makes water condense even behind a droplet separator, eroding the blades. A Hannover study on fuel cell turbines likewise asks for robustness against droplets and lets the turbine set the cathode operating pressure. Ford describes how wet pressure sensors in a fuel cell can freeze and give no or false signals at a cold start. A second sensor lets the controller spot such a reading. No maker documents U355E publicly. A failure of sensor 2 alone mainly removes this cross-check; together with U355D the expander control is blind and power is likely limited.
- What you may notice
- Fuel cell system warning, MIL on
- Fault appears mainly after cold starts
- Reduced power if sensor 1 is affected as well
- Likely causes
- LikelyWiring or connector of sensor 2 corroded by exhaust moisture, open or shorted
- PossibleWater frozen in the sensor port at cold start
- PossibleExpander inlet pressure sensor 2 faulty internally
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €100 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.