Jaguar XJ / XJR MOT Failures: Common Issues & Parts Guide (X350/X358, 2003–2009)

The X350 was a revolutionary Jaguar — the first XJ to ditch the traditional steel body for an aluminium monocoque, making it lighter than the outgoing X308 despite being bigger in every dimension. Available with a 3.0 V6, 3.5 and 4.2 V8s, and the supercharged 4.2 V8 in the XJR and Super V8, it was facelifted as the X358 in 2007 with updated styling and the introduction of the 2.7 TDV6 diesel. With the earliest cars now 23 years old and 9,064 MOT tests recorded in 2024, here's what's failing.

XJ X350 MOT Pass Rate

The X350 holds a 75.0% MOT pass rate — 1.7 percentage points below the UK average of 76.7%. That's significantly worse than its aluminium successor, the X351 (83.3%), but notably better than the steel-bodied S-Type (66.7%) and X-Type (63.7%). The aluminium body means virtually zero structural corrosion — the failures are mechanical wear and age-related rubber degradation.

The median mileage at MOT is 101,970 miles. With 7,320 failure items from 9,064 tests, the X350 averages 0.81 failures per test. The severity split is 86.6% major / 13.4% dangerous — one of the lowest dangerous ratios, meaning failures are overwhelmingly wear items rather than safety-critical issues.

1. Suspension — A Dominant 40.3% of All Failures

Suspension overwhelmingly dominates, accounting for 40.3% of all failure items (2,948 items). The same rubber degradation story as the XK X150.

What Fails

• Suspension joint dust cover deteriorated — 1,347 failures (the #1 item — 18.4% of ALL failures, 1 in 7 cars)
• Suspension pin, bush or joint excessively worn — 646 failures
• Shock absorber bush excessively worn — 151 failures

The dust cover count at 1,347 mirrors the XK X150's pattern — at 15–23 years old, every rubber dust cover on the suspension is perishing. The aluminium body is outlasting the rubber components by a wide margin.

Cars equipped with air suspension (standard on many X350 trims) have additional failure vectors — air springs that leak, compressors that wear, and height sensors that corrode.

What You Need

Tip: A complete rubber refresh — all suspension dust covers, bushes, and shock absorber top mounts — before the MOT addresses nearly 30% of all potential failures. At this age, piecemeal replacement is false economy.

2. Steering — Gaiters Are the #3 Failure

Steering rack gaiter failure is the #3 individual item at 606 failures (8.3%) — the same age-related rubber degradation driving the suspension numbers.

What You Need

3. Brakes — 17.5% of Failures

Brakes account for 17.5% of failure items (1,280 items). Brake pipe corrosion is the standout issue.

What Fails

• Brake pipe corroded — 310 failures (the #4 individual item)
• Brake lining/pad worn below 1.5mm — 158 failures
• Brake binding — 130 failures
• Brake hose ferrule corroded — 118 failures
• Parking brake efficiency below minimum — 77 failures
• Parking brake inoperative on one side — 65 failures
• Leaking brake pipe — 62 failures

The combined brake pipe and hose ferrule corrosion at 428 — and the leaking brake pipe count at 62 — are concerning on a car with an aluminium body. The steel brake lines are the corrosion weak point on an otherwise corrosion-proof car. The parking brake failures (142 combined) reflect the electronic parking brake mechanism seizing.

What You Need

Tip: The aluminium body won't rot, but the steel brake lines will. Replace with Cunifer (copper-nickel) for a permanent fix. Exercise the electronic parking brake regularly to prevent seizure.

4. Lamps & Lighting — 13.2% of Failures

Lighting accounts for 13.2% (966 items).

What Fails

• Headlamp aim outside limits — 170 failures
• Lamp colour/position/intensity non-compliant — 162 failures
• Lamp inoperative — 161 failures
• Headlamp inoperative — 141 failures
• Rear registration plate lamp inoperative — 82 failures

The lamp colour/intensity count at 162 is unusual — possibly reflecting aged xenon bulbs producing the wrong colour temperature, or aftermarket bulbs that don't meet the specification.

What You Need

Tip: Xenon/HID-equipped X350s must have working headlamp washers and self-levelling. Aged xenon bulbs shift colour — if they look pink or blue, replace them. The headlamp washer jets block easily — clear them before the test.

5. Tyres & Wheels — 10.9% of Failures

What Fails

• Tyre seriously damaged — 235 failures
• Tyre tread depth non-compliant — 173 failures
• Tyre cords visible — 140 failures

What You Need

6. Visibility — 5.8% of Failures

What Fails

• Windscreen washers non-functional — 225 failures
• Wiper blade not clearing windscreen — 173 failures

What You Need

7. Emissions & Engine Management — 5.3% of Failures

What Fails

• Engine MIL illuminated — 228 failures (1 in 40 cars)
• Warning device malfunction — 109 failures

On the V8 petrols, common MIL triggers are catalytic converter inefficiency, lambda sensor degradation, and secondary air injection faults. On the 2.7 TDV6 diesel (X358 only), DPF and EGR issues apply.

What You Need

Beyond the MOT: Major X350 Faults That Drive Workshop Visits

Air Suspension Failure

Standard on many X350 trims. The air springs perish, the compressor wears out, and the valve block develops internal leaks. A complete system failure leaves the car sitting on its bump stops. Coil spring conversion kits are available as a permanent alternative.

Timing Chain Issues (4.2 V8 & 4.2 SC V8)

The AJ-V8 engine's timing chains stretch and the tensioners wear — particularly the upper chain on the supercharged models. A cold-start rattle is the warning sign. If the chain jumps, the engine is destroyed. Regular oil changes with the correct specification are essential.

Water Pump & Cooling System (V8 Models)

The same cooling system weaknesses as the XK and XF — coolant enters the water pump bearing housing, the plastic crossover pipe cracks, and the expansion tank fails. The X350's tight engine bay makes access difficult.

Throttle Body Failure (2.7 TDV6)

The 2.7 diesel's throttle body clogs — the same issue as the XF and S-Type. "Restricted Performance" mode and failed DPF regeneration follow.

ZF 6-Speed Gearbox (ZF 6HP26)

The ZF 6-speed develops a shudder on the 2–3 upshift from torque converter wear. A fluid and filter change helps, but eventually the torque converter needs attention.

Electrical & Battery Drain

The X350 is electrically complex and sensitive to battery health. A weak battery causes cascading warning lights. Parasitic drain from modules failing to sleep is common — the seat memory module and the audio amplifier are known culprits.

Window Regulator Failure

The cable-type window regulators are a common failure across all four doors.

XJ X350 MOT Failure Summary — At a Glance

Keeping Your Jaguar XJ X350 on the Road

The X350 was the car that proved aluminium construction could work in a large saloon — and the MOT data confirms it. Structural corrosion is just 0.1% of failures — effectively zero. Compare that to the steel S-Type (3.5%) and X-Type (5.5%), and the aluminium advantage is clear. The X350's body will outlast everything bolted to it.

The failure profile is dominated by rubber degradation — suspension dust covers (18.4%) and steering gaiters (8.3%) account for over a quarter of all failures. A proactive rubber refresh addresses the single biggest category of failure. Beyond that, brake pipe corrosion (the steel lines on an aluminium car), headlamp bulbs, and windscreen washers round out the list.

The X350 remains one of the great used car bargains — a full-size Jaguar flagship with genuine presence, the 4.2 V8's smooth power delivery, and a body that won't rot. At current prices, it's an extraordinary amount of car for the money.

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Service & Maintenance Parts

Data sourced from DVSA anonymised MOT test results (2024 test year, 9,064 tests on X350/X358-era Jaguar XJ models with first use dates 2003–2009). 7,320 individual failure items analysed. Specialist fault data from K Motors and Jaguar workshop reporting.