U355E
Expander Inlet Pressure Sensor 2 Circuit.
- Generic
- Network
- Generic code
- Medium severity
How this code is built
- U
- SystemNetwork
- 3
- Defined bySAE, the same on every car
- 5
- AreaNetwork area 5
- 5E
- FaultThe specific fault in that area
What it means
U355E is defined generically as Expander Inlet Pressure Sensor 2 Circuit. The control unit has detected a fault with the signal or circuit for the second pressure sensor at the inlet of an expander, a component found on only some vehicles with specialised energy-recovery or gas-handling systems. A U-code is normally logged when a signal or data is missing, implausible or not received, so the exact trigger depends on how the manufacturer has set up the system. Check the vehicle-specific documentation to confirm where the sensor is and whether it feeds the control unit directly or over the network.
Symptoms
- Warning lamp on, possibly with a system-specific fault message
- Reduced performance or the car running in a limited-output mode
- Related system not operating or switching itself off
- Other fault codes stored for the same system or for communication
- Intermittent faults that come and go with vibration, heat or damp
Possible causes
- Wiring fault in the sensor circuit (open circuit, short to earth or supply, chafed or corroded wires)likely
- Poor connection at the sensor or control unit connector (corrosion, bent or loose terminals, water ingress)likely
- Faulty expander inlet pressure sensor 2, giving no signal or an implausible onepossible
- Low or unstable supply voltage or poor earth to the sensor or control unitpossible
- Pressure sensor port blocked, leaking or damaged, giving a reading that does not match the expected valuepossible
- Fault in the control unit or an outdated calibration, where the manufacturer lists it as a known causerare
How to diagnose
- Read all stored and pending codes and the freeze frame data, noting whether other codes appear for the same system or for communication.
- Look up the vehicle-specific description of this code and the location of expander inlet pressure sensor 2, as this varies by model and engine.
- Visually inspect the sensor, its wiring and connectors for damage, chafing, corrosion, moisture or heat damage.
- Check the sensor connector terminals for tightness and fit, and clean or repair them if needed.
- With the ignition on, measure the sensor supply, signal and earth against the manufacturer's specification.
- Test the wiring between the sensor and the control unit for continuity and for shorts to earth or supply.
- Check the pressure port and any associated pipework for blockage or leaks, and compare the live pressure reading with a known good value.
- Clear the code, then road test or run the system to see if the fault returns, and check for any applicable software updates.
How to fix
- Repair or replace damaged wiring and renew any faulty connectors or terminals.
- Clean and secure the connections, and seal them against moisture.
- Replace expander inlet pressure sensor 2 if it fails testing.
- Correct any supply voltage or earth fault.
- Clear or repair a blocked or leaking pressure port or pipe.
- Update the control unit calibration only if the manufacturer identifies an outdated or faulty calibration as the cause.
Can I keep driving?
The car can usually be driven carefully for a short time, but the related system may be limited or inactive. Have it diagnosed soon, and stop driving if you see other warnings, a loss of power or unusual noises.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.