Known JLR Fault
Range Rover L322 Sunroof Drain Blockage & ECU Water Damage
Affects
Overview
Water ingress through blocked sunroof drains is one of the most damaging and insidious faults on the Range Rover L322. The sunroof drain channels run through the A and C pillars and can become blocked with debris — causing water to pool in the footwells and, critically, on top of the ECU and other electronic modules mounted under the seats.
Symptoms
- ▶Wet carpets in the footwells — particularly front and rear
- ▶Multiple electrical warning lights appearing after rainfall
- ▶ECU or control module faults with no obvious mechanical cause
- ▶Damp or musty smell inside the cabin
- ▶Water staining on the headliner around the sunroof aperture
- ▶Complete electrical failure after heavy rain — ECU water damage
What Causes It?
- ✕Sunroof drain tubes blocked by leaf debris, moss, or road dirt
- ✕Drain tube disconnection inside the A or C pillar
- ✕Water overflowing from blocked drains onto ECU modules below the seats
- ✕Perished sunroof seals allowing water past the first line of defence
The Solution
JLRMAN clears sunroof drains using compressed air and specialist flush tools, and checks all four drain outlets (two front, two rear) are clear and flowing correctly. We inspect the drain tube connections inside the pillars. Where ECU or module damage has occurred, we carry out a diagnostic scan to identify affected units and advise on replacement or repair options. Prevention — annual drain clearing — is far cheaper than ECU replacement.
How to Prevent It
Clear all four sunroof drain tubes annually with compressed air — a £100 preventive service that avoids potential ECU water damage costing thousands to rectify.
Other Common JLR Faults
Jaguar XF Electrical Problems
Jaguar XF X250 (2008–2015)
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Range Rover Air Suspension Failure
Range Rover L322 (2002–2012)
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Land Rover Discovery 3 & 4 EGR Cooler Failure
Land Rover Discovery 3 TDV6 (2004–2009)
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Range Rover Sport Timing Chain Failure
Range Rover Sport L320 TDV6 (2005–2013)
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Typical Repair Cost
£200–£3,000
Cost varies by model, severity, and parts required. Contact JLRMAN for a no-obligation quote specific to your vehicle.
Experiencing This Fault?
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Related Service
Diagnostics
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