Range Rover L405 Common Problems, Faults and Workshop-Level Diagnosis

The Range Rover L405 spans two distinct technical generations separated by a 2017 facelift. Pre-facelift diesel variants from 2013 to 2016 do not have AdBlue. That warning applies only to post-facelift SDV6 models fitted with SCR.

Across the platform, the most important failures include EAS compressor thermal cutout, air spring seep, DPF blockage in short-cycle diesel use, SDV6 timing chain tensioner wear, ACE or ARC active roll actuator leaks, front upper and lower wishbone wear, EPB actuator seizure, and the documented crankshaft bearing rotation issue on 3.0 diesel units. Serious diagnosis on the L405 requires a JLR-capable scan tool. Generic OBD-II is not enough.

Range Rover L405 at a Glance: Two Generations, One Chassis

The L405 was produced from 2013 to 2022 across two clearly different technical phases. These phases differ in powertrain specification, emissions after-treatment, electronics architecture, and parts interchangeability. Every technical recommendation in this guide must be qualified by generation.

L405 Air Suspension: Compressor, Air Springs and Height Sensors

How the system works

The L405 Electronic Air Suspension uses four corner-mounted air strut units, a Wabco-sourced compressor with integrated dryer and pressure reservoir, four rotary height sensors, and a dedicated EAS ECU. The system provides variable ride height from off-road high to motorway low through Terrain Response and speed-based control logic.

EAS compressor failure

The Wabco compressor is prone to thermal cutout caused by repeated short-cycle operation. When an air spring is seeping, the compressor runs excessively in an attempt to maintain target height. Once thermal protection threshold is reached, the compressor shuts down and the EAS ECU logs a compressor fault. This is a common route to the Suspension Inactive warning.

This is not the same as a slow-rise fault. Slow rise points more toward air spring seal degradation or reduced compressor output. These need to be separated properly during diagnosis.

Air spring failures

Front air springs fail more often than rear units because of steering articulation stress at the lower sleeve-to-piston interface. The classic symptom is uneven ride height after standing overnight, often with a diagonal front droop. If one unit is replaced, confirm height sensor accuracy and perform EAS calibration after installation.

Coil spring conversion

Coil spring conversions exist for high-mileage L405 vehicles where EAS repair economics no longer make sense. They are a cost-reduction option, but the consequences are permanent.

• All Terrain Response height modes are lost
• Wade Sensing loses height-input data and may log faults
• Automatic motorway lowering is removed
• Persistent DTCs remain in the EAS ECU
• Type approval or inspection implications may apply in some EU markets

ACE / ARC: The Expensive Clunk Many Guides Miss

The L405 is often fitted with ACE, also referred to as Active Roll Control on some variants. This hydraulic anti-roll system uses electronically controlled actuators on the anti-roll bars to actively resist body roll. It is separate from EAS and has its own fault profile.

What fails

The actuator seals and hydraulic line connections can leak, especially beyond roughly 90,000 km. Failures usually present in two ways:

1. Fluid leak: hydraulic fluid visible around the actuator or subframe, often with the pump running continuously
2. ACE inactive fault: pressure drops below threshold, the system disables, and body roll becomes noticeably worse

If you have a front or rear clunk that does not trace clearly to wishbones, hub bearings or top mounts, inspect the ACE actuators before condemning other suspension parts.

Repair approach

Before replacing an actuator, check the line unions for corrosion-based seepage and confirm only correct ACE-specification fluid has been used. Wrong fluid accelerates seal damage. ACE faults must be read with a JLR-capable diagnostic tool.

L405 3.0 Diesel: TDV6 and SDV6 Engine-Specific Faults

The crankshaft bearing rotation issue

This is the most serious failure mode in the L405 3.0 diesel range. On both the TDV6 and SDV6, documented cases exist where the crankshaft bearing shell rotates in its housing, leading to oil film collapse and rapid crank journal damage.

Early signs include a low rhythmic knock from the lower engine, reduced oil pressure, and metallic contamination in oil analysis. Once bearing rotation starts, catastrophic failure can follow quickly.

Key risk factors:

• Extended oil intervals
• Incorrect oil specification
• Urban use with sludge-restricted oil passages on high-mileage engines

TDV6 306DT specific failure points

• EGR valve and cooler: sticking valves, rough idle, black smoke, and cooler leakage causing coolant ingress into the inlet
• Injector return seals: fuel dilution of engine oil, rising oil level, fuel smell in oil
• HPFP wear: hard starting, power loss, and low rail pressure faults on higher-mileage units

SDV6 306PS / 306DT-2 specific failure points

• Timing chain tensioner wear: cold-start chain rattle that clears after 10 to 15 seconds is not normal and must not be ignored
• Injector return seals and EGR faults: shared failure pattern with the earlier engine family

DPF Regeneration and AdBlue / SCR: What Applies to Which L405

DPF applies to all diesel variants

The diesel exhaust system uses a DOC and DPF, with SCR added on post-facelift models. Passive regeneration needs sustained exhaust temperature and typically requires steady higher-speed driving. Urban-only use prevents passive regeneration and raises soot loading.

The ECU can command active regeneration, but it needs correct coolant temperature, sufficient vehicle speed, and suitable operating conditions. Repeatedly interrupted active regen will eventually require a forced regeneration through a diagnostic tool.

AdBlue and SCR only apply to post-facelift diesel models

Pre-facelift L405 diesel models from 2013 to 2016 do not have AdBlue. That warning only applies to MY2017 onwards SDV6 models fitted with SCR.

The warning sequence is staged. The vehicle does not stop while driving.

1. First warning: approx. 2,400 miles / 3,800 km remaining
2. Second warning: approx. 1,200 miles / 1,900 km remaining
3. Restart inhibit: only after the tank is depleted and the engine is switched off

Fluid quality matters. Incorrect or contaminated AdBlue causes injector crystallisation and pump corrosion. Repeat NOx sensor faults often point to a dosing or contamination issue, not just the sensor itself.

V8 Petrol Cooling System: The Plastic Pipe Problem

The 5.0-litre supercharged V8 has a known weak point in the plastic coolant outlet flange and Y-piece pipework beneath the supercharger. Heat cycling causes these parts to fatigue and crack, often beyond roughly 80,000 km.

Because the leak sits beneath the supercharger, coolant often evaporates on hot surfaces rather than dripping visibly. By the time the warning is seen, the engine may already have been overheated.

Inspect the area cold for staining or residue and strongly consider preventive replacement with uprated aluminium parts before failure occurs.

L405 Electrical Faults: Terrain Response, InControl and Door Modules

Pre-facelift infotainment architecture

Pre-facelift L405 models use a MOST optical ring for infotainment. A single failed node can take down the whole ring, causing blank media screen behaviour, loss of rear camera, and missing climate display through the infotainment interface.

Post-facelift infotainment architecture

Post-facelift models move to Ethernet-based HMI. MOST-specific failures no longer apply, but software and communication faults remain relevant.

Terrain Response switch / TRNMOD

The Terrain Response selector is an encoded electronic input, not a simple mechanical switch. Moisture ingress under the bezel can cause intermittent or failed mode selection. Replacement usually requires module coding.

Door modules

Driver and passenger door modules are vulnerable to moisture ingress from failed door membranes. Before replacing a module, check membrane sealing and connector dryness. A new module on a wet connector is a repeat failure waiting to happen.

Bonnet latch sensor and limp mode

A failed bonnet latch sensor logs a BCM fault and can trigger a bonnet open or security warning. It does not cause limp mode. Limp mode is a PCM or TCM protection strategy and must be diagnosed in the powertrain or transmission system.

L405 Suspension, Hubs and EPB: What Wears and What Not to Do

Front double-wishbone wear

Both upper and lower front arms are wear items and should be inspected together.

• Lower wishbone: clunk under braking or take-off, vague steering, directional wander
• Upper arm ball joint: lighter, sharper knock over potholes or speed humps

Hub bearings

Hub bearing failure presents as a speed-dependent drone or rumble that changes with lateral loading. The L405 uses integrated hub assemblies rather than separately pressed bearings.

Electronic Parking Brake

The L405 uses caliper-integrated rear EPB actuator motors. Rear brake pistons must be electronically retracted using a JLR-capable diagnostic tool before the caliper is opened.

Diagnostic Tools for the L405: Why Generic OBD-II Is Not Enough

The L405 uses multiple vehicle networks, including CAN, LIN, MOST on earlier models, and Ethernet on later ones. A generic OBD-II reader mainly sees the engine gateway side. It does not give meaningful access to the rest of the vehicle.

The following modules are typically invisible to generic OBD-II:

EAS ECU, EPB ECU, BCM, TCM, ACE / ARC ECU, TRNMOD, door modules, SCR controller, Terrain Response modules

L405 Common Problems: Symptoms and Causes

L405 Maintenance and Torque Reference

Frequently Asked Questions

These are the most common owner and workshop questions about Range Rover L405 faults, AdBlue applicability, rear brake service procedure, suspension diagnosis, and V8 coolant leaks.

Published: June 2025 | Last updated: March 2026