2004 Jaguar XJ 4.2L Petrol · BP04 XDY

Structural corrosion on the underside and progressive wear of braking components represent the primary mechanical risks for this vehicle, as evidenced by the 2026-05-05 MOT pass which flagged a corroded rear sub-frame and thinning handbrake pads. While the vehicle has maintained a passing status since 2018, the advisory history shows a recurring pattern of underside corrosion, moving from surface-level observations in 2018 and 2019 to a specific warning regarding the structural integrity of the rear sub-frame in the most recent test. This trend suggests that while the vehicle remains roadworthy, the degradation of the chassis and sub-frame components is a continuing issue that requires close monitoring. The recorded mileage of 100,746 miles over a 22-year period equates to an average annual usage of approximately 4,579 miles. This is significantly lower than the UK average, which can imply less frequent mechanical movement of seals and suspension components. Such a low-mileage profile, combined with the specific advisory in 2019 regarding oil residue on the undertray, may indicate periods where the vehicle has been stationary, potentially allowing moisture to accelerate the corrosion noted on the underside and sub-frame. A prospective buyer should prioritise a thorough inspection of the vehicle's underbody, specifically focusing on the rear sub-frame area mentioned in the 2026 advisory. During a test drive, pay close attention to any knocking, clunking, or irregular vibrations coming from the rear of the car when traversing uneven surfaces, as these can be symptoms of weakened mounting points or degraded sub-frame integrity. The advisory regarding thinning handbrake pads also necessitates a functional check; the handbrake should be tested for its ability to hold the vehicle firmly on an incline, and any excessive travel or lack of resistance in the lever should be noted. Further attention should be given to the steering and front suspension, following the 2018 failure involving a split track rod end ball joint dust cover. While this specific defect was rectified, the history of steering component wear warrants a check for any wandering or pulling to one side during straight-line driving, or any light clicking sounds when turning the steering wheel at low speeds. Additionally, the recurring windscreen damage noted across multiple years suggests a need to check for any new chips that could compromise visibility or lead to structural cracks in the glass.