ASE A4 Suspension and SteeringSuspension System Diagnosis and RepairMedium
A vehicle with an air suspension system exhibits a consistent sag on the right front corner overnight, but the compressor eventually raises it to the correct height once the engine is started. There are no DTCs related to the compressor or valve block. What is the MOST likely cause of this specific symptom?
- AA small leak in the right front air spring or line
- BFaulty air suspension compressor relay
- CMalfunctioning ride height sensor on the left front
- DSticking pressure relief valve in the compressor
Show answer & explanationAnswer & explanation
Correct answer: A. A small leak in the right front air spring or line
A consistent sag on one corner overnight, which then corrects itself when the compressor runs, is a classic indication of a slow air leak in that specific air spring or its associated air line. The compressor can overcome the leak once active, but the leak allows pressure to escape over time.
Why the other options are wrong
- B. A faulty compressor relay would prevent the compressor from running at all, leading to multiple low corners or no inflation.
- C. A malfunctioning ride height sensor on the LEFT front would affect the LEFT front corner's height, not the right front, and might trigger a DTC.
- D. A sticking pressure relief valve would affect the entire system's ability to hold pressure or could cause compressor over-pressurization, not a single corner sag.
Air Suspension Leak
A leak in an air spring, air line, or fitting allows air to escape, causing a specific corner or the entire vehicle to sag, often noticed after parking overnight.
- Can be slow or rapid
- Often audible or detectable with soapy water
- Causes uneven ride height and compressor overwork
Memory trick: Air-bag's a-leakin', the corner's a-sinkin'.