Air Compressor Status
Check Compressor control by external tester activation. Check control line. Check compressor. Exchange or repair faulty part (compressor, line, protection valve housing or ECU).
What you'll see
No driver-visible symptom recorded.
System reaction
The unit switches to degraded mode: Alternative Unload Strategy (both solenoids are activated in parallel). Except the changed method for pressure regulation no influence on functionality of 'advanced' variant. On 'high capacity' variant only the regeneration orifice can be utilized to lower the system pressure. If the compressor delivers more air than it can be released through the orifce, pressure will still rise until it reaches the opening pressure of the safety valve.
Diagnostic depth
Pressure rises 3 times above a parametrized value even with a shut-off compressor or the pressure reaches one time the parametrized value for overpressure level.
Undeteced internal electrical or mechanical fault or external compressor control line failed or compressor control failed in compressor.