Range Rover Air Suspension: Compressor, Valve Block, and Air Spring Diagnosis

The Electronic Air Suspension (EAS) system fitted to Range Rover, Range Rover Sport, and Discovery models is a closed pneumatic system comprising an air compressor, reservoir tank, valve block, four air springs, height sensors, and a suspension control module. Each component has distinct failure modes. Replacing the wrong one wastes money and leaves the root cause unresolved.

Short Answer

Air suspension faults fall into three categories: air leaks (springs, valve block O-rings, airline connections), compressor failure (usually secondary to a leak), and electronic faults (height sensors, control module, wiring). The most common mistake is replacing the compressor when the actual fault is a leaking air spring. The compressor fails because it runs continuously trying to compensate for the leak — it is a victim, not the cause. Correct diagnosis requires identifying the leak source first (using soapy water, ultrasonic detection, or Pathfinder active tests), then assessing the compressor's condition, and finally verifying the electronic control system. This sequence matters. Fit a new compressor to a vehicle with a leaking spring, and the new compressor will burn out within months.

What You'll Learn

• The complete architecture of JLR's EAS system across L322, L405, and L460 Range Rovers
• How the compressor, valve block, reservoir, and air springs interact as a system
• Why compressor failure is almost always a secondary fault
• The three methods for locating air leaks: visual, ultrasonic, and diagnostic active testing
• Valve block internal O-ring degradation and cross-leak symptoms
• Height sensor failure modes and their effect on ride height control
• Cost-effective repair strategies vs full system overhaul

Real-World Scenarios

Case 1: L405 Range Rover — Compressor Replaced Twice, Still Dropping

A 2015 L405 Range Rover Autobiography arrived having had two compressors fitted in 18 months — both at other garages. The vehicle was still dropping on the rear left overnight. Each garage diagnosed "compressor failure" because the compressor was not running when they checked — it had already overheated and shut down on thermal protection. The actual fault was a split in the rear left air spring bellows at the lower fold, only visible with the suspension at full extension. The spring had been leaking slowly for over two years, and each replacement compressor burned out trying to maintain height against the leak. We replaced the leaking air spring (£185 quality aftermarket unit), assessed the current compressor (third one — still functional as it was relatively new), and the vehicle held height perfectly. Two compressors were destroyed unnecessarily because the leak was never found.

Case 2: Range Rover Sport — Valve Block Cross-Leak

A 2017 Range Rover Sport SDV6 presented with an unusual symptom: the front left would rise while the rear right would drop, intermittently. No external air leak could be found — the system held overall pressure. Using Pathfinder, we performed individual corner inflation and deflation tests. We discovered that the valve block had an internal cross-leak between the front left and rear right circuits. The internal O-rings within the valve block had degraded, allowing air to transfer between ports. We rebuilt the valve block with a new O-ring kit (£45 in parts) rather than replacing the entire unit (£650+ new from JLR). The cross-leak was eliminated, and the system was restored to correct operation.

Case 3: L322 Range Rover — Height Sensor Linkage Failure

A 2010 L322 Range Rover displayed "Suspension Fault — Normal Height Only" and the vehicle sat approximately 20mm low on the front right. No leak was present. The fault was a snapped height sensor linkage arm on the front right suspension. The plastic ball joint connecting the sensor arm to the suspension lower arm had fractured, so the sensor was reporting a fixed position regardless of actual ride height. The control module could not determine the correct height of that corner, so it disabled the automatic levelling system and locked the vehicle at its current position as a safety measure. A new height sensor linkage (£35 part) and a recalibration via SDD resolved the fault completely. This is a common failure on L322 models and is frequently misdiagnosed as an air spring or compressor issue.

Why Inspection and Diagnostics Matter

Air suspension diagnosis on JLR vehicles is a systematic process that must be followed in order. The sequence is: identify leaks first, assess compressor condition second, verify electronics third. Skipping steps leads to misdiagnosis and wasted expenditure.

At Nine Torque, we use a combination of physical inspection and manufacturer-level diagnostics. Pathfinder allows us to perform active tests on the air suspension system — we can command individual corners to inflate and deflate independently, monitor compressor current draw in real-time (a healthy compressor draws 20-25A; one with worn piston rings draws 30A+), read exact height sensor values in millimetres, and run the system's built-in leak-down test. These active tests are not available on generic diagnostic tools.

We supplement the electronic diagnosis with physical leak detection. For slow leaks that are difficult to detect by ear, we use an ultrasonic leak detector that can identify air escaping at rates as low as 5ml per minute. For accessible joints and springs, soapy water spray remains the fastest and most reliable method.

Our approach to air suspension repair is pragmatic. We use quality aftermarket air springs from proven suppliers (Arnott, Dunlop OE) rather than insisting on JLR-branded parts at twice the price. The compressor is only replaced if it has demonstrable wear — not as a precaution. Valve blocks are rebuilt where possible rather than replaced whole. This approach keeps repair costs realistic while delivering long-term reliability. If your Range Rover is showing suspension warnings or sitting unevenly, contact us for a proper diagnosis before committing to expensive parts.

Frequently Asked Questions

How long should a Range Rover hold its ride height when parked?

A healthy system should hold its set height for a minimum of 5-7 days with no measurable drop. If the vehicle drops noticeably overnight (more than 10-15mm on any corner), there is a leak in the system. Even a small overnight drop that self-corrects on startup indicates a leak that will eventually worsen and damage the compressor.

Can I convert my Range Rover from air suspension to coil springs?

Coil spring conversion kits exist for the L322 and some L405 models. However, you lose all ride height adjustment, automatic levelling, off-road height modes, and the ability to lower for motorway driving. The ride quality also changes significantly — the compliance and isolation of air springs cannot be replicated by coils. We generally recommend repairing the air system unless the vehicle is exclusively used as a workhorse and the owner accepts the compromises.

Are aftermarket air springs as good as JLR genuine parts?

The established aftermarket suppliers (Arnott, Dunlop — who actually manufacture the OE springs for JLR) produce air springs that are functionally identical to the genuine parts. In some cases, the aftermarket versions incorporate updated rubber compounds that address known failure points in the original design. We have fitted hundreds of aftermarket springs with excellent long-term results. The cost saving is typically 40-60% versus JLR genuine parts.

Why does my compressor keep running after the vehicle reaches the correct height?

The compressor should run for 30-90 seconds during a height adjustment and then stop. If it runs continuously or cycles on and off repeatedly, the system is losing air faster than the compressor can supply it. This is an urgent symptom — the compressor is overworking and will fail from thermal overload if the leak is not addressed promptly. Do not ignore a constantly running compressor. The leak source must be identified and repaired before the compressor is damaged.

Can I drive with the "Suspension Fault" warning displayed?

It depends on the specific fault. If the vehicle is sitting at a level height and the warning is related to a sensor or minor electronic fault, gentle driving to a specialist is acceptable. If the vehicle is visibly leaning, sitting on its bump stops on any corner, or displaying "Maximum Speed Limited" alongside the suspension warning, the vehicle should not be driven — the handling and braking characteristics are compromised. Have it transported to a specialist. In either case, continued driving accelerates compressor wear and can turn a minor leak into a major system failure.