Possible Causes
- Signal plausibility failure
- Reservoir valve block pipes incorrectly installed (unions reversed)
- Exhaust valve stuck closed
- Exhaust valve does not hold minimum retention pressure
- Air suspension air supply unit exhaust valve circuit - Short circuit to ground, short circuit to power, open circuit, high resistance
- Gallery pipe blocked/damaged
- Air suspension exhaust silencer or exhaust pipe blocked/restricted
- Axle valve block pipes connected incorrectly
- Pressure sensor fault