What it means
The inlet pressure sensor circuit signal for the alternative fuel rail pressure regulator is higher than expected.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
The regulator inlet pressure sensor reports incoming alternative-fuel rail pressure to the control module. This circuit-high code sets when its signal exceeds the expected range, which can happen if the signal is shorted to battery voltage or the sensor circuit is open.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open pressure sensor
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine or alternative-fuel system warning light
- Rough running or hesitation on alternative fuel
- Alternative-fuel operation may be limited
How to diagnose it
- Review freeze-frame and live inlet-pressure data to confirm the high signal and note whether it is constant or intermittent.
- Inspect the pressure sensor connector and harness for loose or corroded terminals, damaged insulation, or contact with a powered wire.
- Check for an open sensor connection or poor terminal contact using the vehicle's wiring information.
- With the circuit safely isolated as directed, test the signal wire for a short to battery voltage and check circuit continuity.
- Measure sensor output and circuit supply and ground against the manufacturer's specification to identify an open sensor or wiring fault.
Common fixes
- Secure the sensor connector and repair loose or corroded terminals.
- Repair a signal wire shorted to battery voltage or damaged harness insulation.
- Repair an open circuit or poor connection in the sensor wiring.
- Replace the inlet pressure sensor if it is open internally and fails the manufacturer's checks.
Can I keep driving?
The module may misread regulator inlet pressure, leading to hesitation or rough running and limited alternative-fuel operation. Avoid hard acceleration and stop safely if engine performance becomes unpredictable.
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.