Jaguar XJ X350/X358Saloon2003–2009Every engine fitted to the X350 and facelifted X358 – from the 3.0-litre V6 and 3.5/4.2-litre V8s to the supercharged 4.2 XJR and the 2.7-litre diesel that brought new buyers to the brand. Real UK replacement costs, honest reliability data, and the cooling system weaknesses that define this aluminium-bodied generation. Backed by real UK X350/X358 enquiries in 2025 [JAG-VERIFIED].
X350/X358Enquiries (2025)JAG-VERIFIEDSaloon
6Engine Codes
Part ofEngine Finders
Every engine fitted to the X350 and X358 – from the entry-level V6 to the supercharged XJR flagship.
Overview
The Jaguar XJ X350, launched in 2003, was a landmark car – the first production vehicle to use an aluminium monocoque chassis constructed with aerospace-style rivet-bonding, making it 40% lighter and 50% stiffer than its steel-bodied X308 predecessor.
It retained the classic Jaguar silhouette while hiding a host of technological advances beneath the skin, including adaptive air suspension, fibre-optic data transmission and a range of all-new V6, V8 and diesel engines. A 2007 facelift (X358) brought updated styling and electronics.
Key Facts
Platform
Jaguar aluminium monocoque (X350/X358)
Predecessor
Jaguar XJ X308
Successor
Jaguar XJ X351 (2010–2019)
Sibling body styles in this generation
None (X350/X358 is the sole XJ body code for this generation)
Market Intelligence
The X350/X358 generated real UK engine enquiries in 2025 [JAG-VERIFIED], with the 2.7-litre diesel and 4.2-litre V8 accounting for the majority of demand as these cars enter modern classic territory.
Best Diesel Overall
AJD (2.7 TDVi, 2005–2009) – "The 2.7-litre V6 diesel was a game-changer for the XJ – it brought 40+ mpg economy to the big cat for the first time. Smooth, torquey and reasonably refined, it's the one to choose for high-mileage use. Just budget for crankshaft bearing checks – the Achilles heel of this Ford/PSA unit."
“”
Who it's for: buyers who want XJ luxury with diesel economy.
Best Petrol Overall
AJ33/AJ34 (4.2 naturally aspirated V8) – "The 4.2-litre V8 is the sweet spot of the X350 range – 300 hp, 411 Nm of torque, and none of the supercharger complexity of the XJR. The cooling system is the only real demand – replace the plastic water pump and thermostat housing proactively."
“”
Who it's for: buyers who want effortless V8 power without the XJR's maintenance bills.
Highest Risk
AJD (2.7 TDVi diesel) – "The Ford/PSA diesel can suffer from crankshaft bearing failure – the mainshaft bearings can spin, starving the engine of oil and potentially snapping the crank. This is a catastrophic failure requiring a full engine replacement. Early warning signs include a knocking noise from the bottom end."
“”
Who it's for: only buyers who have confirmed a clean oil analysis and no bottom-end knock.
Most Expensive Failure
AJ34S (4.2 supercharged V8) – "The supercharger, intercooler and timing chain components combine to make this the most expensive X350 engine to maintain – a full replacement can exceed £9,000. The supercharger coupler can wear, and cooling system failures are common."
“”
Who it's for: buyers who want XJR performance and have a dedicated maintenance budget.
Best Value
AJ30 (3.0 V6) – "The entry-level V6 delivers 238 hp, returns reasonable economy and is the cheapest X350 to run and maintain. It lacks the V8's effortless torque, but for wafting around town, it's more than adequate – and it avoids the diesel's crankshaft worries."
“”
Who it's for: buyers who want XJ presence on a budget.
Best Diesel Overall
AJD (2.7 TDVi, 2005–2009) – "The 2.7-litre V6 diesel was a game-changer for the XJ – it brought 40+ mpg economy to the big cat for the first time. Smooth, torquey and reasonably refined, it's the one to choose for high-mileage use. Just budget for crankshaft bearing checks – the Achilles heel of this Ford/PSA unit."
“”
Who it's for: buyers who want XJ luxury with diesel economy.
Best Petrol Overall
AJ33/AJ34 (4.2 naturally aspirated V8) – "The 4.2-litre V8 is the sweet spot of the X350 range – 300 hp, 411 Nm of torque, and none of the supercharger complexity of the XJR. The cooling system is the only real demand – replace the plastic water pump and thermostat housing proactively."
“”
Who it's for: buyers who want effortless V8 power without the XJR's maintenance bills.
Highest Risk
AJD (2.7 TDVi diesel) – "The Ford/PSA diesel can suffer from crankshaft bearing failure – the mainshaft bearings can spin, starving the engine of oil and potentially snapping the crank. This is a catastrophic failure requiring a full engine replacement. Early warning signs include a knocking noise from the bottom end."
“”
Who it's for: only buyers who have confirmed a clean oil analysis and no bottom-end knock.
Most Expensive Failure
AJ34S (4.2 supercharged V8) – "The supercharger, intercooler and timing chain components combine to make this the most expensive X350 engine to maintain – a full replacement can exceed £9,000. The supercharger coupler can wear, and cooling system failures are common."
“”
Who it's for: buyers who want XJR performance and have a dedicated maintenance budget.
Best Value
AJ30 (3.0 V6) – "The entry-level V6 delivers 238 hp, returns reasonable economy and is the cheapest X350 to run and maintain. It lacks the V8's effortless torque, but for wafting around town, it's more than adequate – and it avoids the diesel's crankshaft worries."
“”
Who it's for: buyers who want XJ presence on a budget.
Most Overlooked
AJ33 (3.5 V8) – "The 3.5-litre V8 is the forgotten engine of the X350 range – European-market only, it delivers 258 hp and V8 refinement without the 4.2's thirst or the XJR's complexity. Most buyers default to the 4.2, but the 3.5 is a genuine bargain."
“”
Who it's for: buyers who want V8 character without the running costs of the larger unit.
The X350/X358 rule
A £3,000–£5,500 4.2 V8 recon against a £3,000–£8,000 X350 sits at 38–183% of the car's value. On a sub-£4,000 example, that brushes our 60% Jaguar threshold – we'll honestly tell you to walk away unless the car is exceptional. Against a £10,000+ low-mileage example, the same recon drops to a routine 30–55% – a repair decision, not a financial one. Always prioritise cars with documented cooling system work.
Key Takeaways
Which X350/X358 Costs Least To Own?
AJ30 (3.0 V6) – cheapest entry, simplest maintenance.
Which X350/X358 Costs Most To Own?
AJ34S (4.2 SC) – supercharger and cooling system bills add up fast.
Which X350/X358 Is Best Value?
AJ33 (3.5 V8) – the sweet spot between V8 character and running costs.
Cooling
System Failures (All Petrol Engines)
Affected models:
X350/X358 V6 and V8 petrol engines (all years).
Typical failure mileage:
60,000–100,000 miles.
Root cause:
The water pump impeller was originally made from plastic – it disintegrates over time and sends debris through the cooling system. The thermostat housing is also plastic and can crack, releasing coolant. Both can lead to overheating and catastrophic engine failure.
Tiered Cost Table
Preventative (Repair)
Dealer
Specialist
£1,200–£2,000
£400–£800
Catastrophic (Replacement)
Dealer
Specialist
£7,000–£12,000
£3,000–£5,500
Our Recommendation
On any X350/X358 petrol, replace the water pump and thermostat housing proactively at 60,000–80,000 miles – £400–£800 now is dramatically cheaper than the £3,000+ replacement that follows an overheat. Always fit the upgraded aluminium impeller pump.
Air
Suspension Compressor Failure (All Models)
Affected models:
All X350/X358 variants (2003–2009).
Typical failure mileage:
60,000–100,000 miles.
Root cause:
The Teflon ring around the air compressor piston wears thin, preventing a proper seal. The compressor works harder to maintain ride height, eventually failing. Symptoms include an "Air Suspension Fault" message and amber warning light, with diagnostic codes C2302 or C2303.
Tiered Cost Table
Preventative (Repair)
Dealer
Specialist
£1,500–£2,500
£500–£1,200
Catastrophic (Replacement)
Dealer
Specialist
£3,000–£5,000
£1,500–£3,000
Our Recommendation
At the first sign of an "Air Suspension Fault" warning, have the compressor inspected immediately – a £500–£1,200 repair is far cheaper than the £1,500–£3,000 replacement that follows if ignored. Replace the relay at the same time.
AJD
2.7 TDVi Crankshaft Bearing Failure
Affected models:
X350/X358 2.7D (2005–2009).
Typical failure mileage:
80,000–150,000 miles.
Root cause:
The Ford/PSA diesel engine can suffer from mainshaft bearing failure – the bearings spin, starving the engine of oil and potentially snapping the crankshaft. This is a catastrophic failure requiring a full engine replacement.
Tiered Cost Table
Preventative (Repair)
Dealer
Specialist
£800–£1,500
£400–£800
Catastrophic (Replacement)
Dealer
Specialist
£5,000–£8,000
£2,500–£4,500
Our Recommendation
If you're considering a diesel X350/X358, have a full oil analysis and crank bearing inspection performed before purchase. Any knocking from the bottom end is a red flag – walk away. Regular oil changes (every 6,000 miles) are essential.
Suspension
Wishbone Bushes (All Models)
Affected models:
All X350/X358 variants (2003–2009).
Typical failure mileage:
50,000–80,000 miles.
Root cause:
The double-wishbone suspension uses rose joints on some bushes, which have a life expectancy of around five years. Symptoms include nervousness over bumps, knocking on rough roads, or MOT failures.
Tiered Cost Table
Preventative (Repair)
Dealer
Specialist
£1,000–£2,000
£500–£1,000
Catastrophic (Replacement)
Dealer
Specialist
£2,500–£4,000
£1,200–£2,500
Our Recommendation
Have the suspension bushes inspected at every MOT – a £500–£1,000 repair is cheap insurance against a £1,200–£2,500 replacement. Always get a four-wheel alignment after any suspension work.
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£1,800–£9,000 supply only .
[JAG-QUOTE]
Most Common Failures
Live FeedJaguar XJ8 4.2
AJ34
5
enquiries
Jaguar 2.7D
AJD
3
enquiries
Jaguar XJR
AJ34S
2
enquiries
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£1,800–£9,000 supply only .
[JAG-QUOTE]
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£1,800–£9,000 supply only .
[JAG-QUOTE]
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£1,800–£9,000 supply only .
[JAG-QUOTE]
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£1,800–£9,000 supply only .
[JAG-QUOTE]
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£1,800–£9,000 supply only .
[JAG-QUOTE]
Most Common Failures
Live FeedJaguar XJ8 4.2
AJ34
5
enquiries
Jaguar 2.7D
AJD
3
enquiries
Jaguar XJR
AJ34S
2
enquiries
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