What it means
Generic fault on the inlet pressure sensor 1 of the expander (turbine recovering energy from the cathode exhaust on FCEVs).
At a glance
- Usually lights the warning light of the system that lost communication
How it works
Expander inlet pressure sensor 1 measures pressure at the expander inlet, where the fuel-cell cathode exhaust drives an energy-recovery turbine. The control module monitors communication with sensor 1 and sets this code when its signal or data path is unavailable or faulty.
Common causes
Most likely first.
- Sensor failed
- Gateway module routing CAN messages incorrectly
- CAN terminating resistor (120 Ω) drifted out of spec
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
How to diagnose it
- Record freeze-frame data and scan all modules for related communication codes to see whether the fault is isolated to expander inlet pressure sensor 1.
- Compare live data from expander inlet pressure sensor 1 with sensor 2 and operating conditions, looking for a missing or implausible reading.
- Inspect sensor 1's connector and harness at the expander inlet for moisture, corrosion, loose pins, or heat and vibration damage.
- Check sensor 1's power, ground, and signal circuits against the manufacturer's specification.
- If multiple modules or sensors report communication faults, test gateway routing and the CAN network, including terminating resistance, to the manufacturer's specification.
Common fixes
- Secure or repair the expander inlet pressure sensor 1 wiring.
- Clean or repair corroded terminals at sensor 1.
- Replace expander inlet pressure sensor 1 if its wiring and supply circuits are sound but its data remains faulty.
- Repair a confirmed gateway or CAN network fault.
Can I keep driving?
Avoid high-load driving if the vehicle reports fuel-cell or expander warnings, reduced power, or unstable operation, since the controller may restrict energy recovery or fuel-cell output. Stop safely if shutdown warnings appear and arrange diagnosis.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.