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Rear of my 2017 GX 460 sags overnight, 'Check Air Suspension' light

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Mike T. · rep 0 · May 25, 3:27 AM · 1 replies · solved · Question

Vehicle: 2017 Lexus GX 460 Premium

Hey guys,

I'm dealing with a frustrating issue on my 2017 Lexus GX 460 Premium. For the past few weeks, I've noticed that the rear of the vehicle sags significantly overnight. When I start it up in the morning, I can hear the air compressor kick on, and it slowly raises back to normal height. However, the 'Check Air Suspension' warning light has also started coming on intermittently.

It seems to hold air fine once it's up, but that overnight sag is getting worse. I'm worried about driving it with a potentially failing air suspension system. The ride quality also feels a bit stiffer than usual.

Has anyone experienced this with their GX 460? What should I be looking for?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:27 AM

0

ClearTheCode admin answer:

An overnight sag and a 'Check Air Suspension' light on your 2017 Lexus GX 460 Premium are classic symptoms of a problem within the rear air suspension system. This system relies on a delicate balance of air pressure and electronic control.

Common Causes:

  • Leaking Air Springs (Air Bags): This is the most frequent culprit. Over time, the rubber air springs can develop small cracks or holes, allowing air to slowly leak out when the vehicle is parked. The compressor then has to work harder to re-inflate them.
  • Faulty Air Compressor: While the compressor might still be working, it could be weak or struggling to maintain pressure due to internal wear. However, the sag usually points to a leak first.
  • Leaking Air Lines or Fittings: The air lines connecting the compressor to the air springs, or the fittings themselves, can develop leaks.
  • Height Sensors Malfunction: The height sensors tell the air suspension computer the current ride height. If a sensor is faulty, it might send incorrect readings, causing the system to try and compensate or trigger a warning. This is less likely to cause a sag but could contribute to the warning light.
  • Air Suspension Relay Issues: A faulty relay can cause the compressor to run continuously or not at all, but usually doesn't directly cause a sag unless it's preventing proper inflation.

Potential OBD Codes:

When the 'Check Air Suspension' light illuminates, the system typically stores diagnostic trouble codes (DTCs). Common codes related to air suspension issues include:

  • C1721: Air Suspension Compressor Malfunction
  • C1723: Air Spring Malfunction (often indicating a leak)
  • Other codes related to height sensor circuits or pressure sensor faults.

Troubleshooting Steps:

  1. Visual Inspection: Look for visible cracks or tears on the rubber air springs in the rear. You can also spray soapy water on the air springs and lines while the system is pressurized (engine running, in 'N' or 'P') to look for bubbles indicating a leak.
  2. Listen for Leaks: With the engine off in a quiet environment, listen for hissing sounds from the rear suspension.

When to See a Shop:

It's highly recommended to take your GX 460 to a Lexus dealership or a reputable independent shop specializing in Lexus vehicles. A technician can use a diagnostic scanner to retrieve specific trouble codes, which will pinpoint the exact component causing the issue. They can then perform a smoke test or further leak detection to confirm the source of the air loss. Driving with a compromised air suspension can lead to uneven tire wear, poor handling, and potentially damage the air compressor from overworking.

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