What it means
The inlet pressure sensor signal for the alternative fuel rail pressure regulator is outside the expected range or does not behave as 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 measures pressure entering the alternative-fuel rail pressure regulator, and the control module checks whether its reading is plausible and responds as expected. This range/performance code sets when the signal is out of the expected range or does not track pressure correctly, even without a simple circuit-low or circuit-high fault.
Common causes
Most likely first.
- Sensor zero drifted
- Sensor mounting loose - bias offset
- Sensor element aged beyond calibration window
Symptoms
- Check-engine or alternative-fuel system warning light
- Rough running or hesitation on alternative fuel
- Reduced fuel economy
How to diagnose it
- Review freeze-frame and live inlet-pressure data for readings that are biased, implausible, or slow to respond when alternative-fuel operation changes.
- Inspect the sensor connector and wiring for poor contact or damage that could distort an otherwise plausible signal.
- Check that the inlet pressure sensor is securely mounted and that its installation is not creating a biased reading.
- Compare the sensor reading with the manufacturer's specified pressure check, following the required fuel-system safety procedure.
- Test the sensor's response across the specified operating conditions and compare it with the manufacturer's calibration limits.
Common fixes
- Secure the pressure sensor mounting if it is loose.
- Repair poor connector contact or damaged sensor wiring.
- Replace a sensor that has drifted or responds outside the manufacturer's specification.
- Correct any confirmed installation issue that biases the inlet-pressure reading.
Can I keep driving?
The engine may hesitate or run roughly on alternative fuel, and the system may limit operation or power. Avoid hard acceleration and arrange prompt diagnosis, especially if the engine's response becomes unreliable.
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.