How much does a Jaguar XJ 3.0 SC Petrol engine replacement cost in the UK?

A reconditioned XJ 3.0 SC engine typically costs £4,500–£7,500 supply only. Fitting adds £2,000–£3,500 depending on location and workshop rates. Customers have reported dealer quotes of around £15,000–£30,000 for engine replacement. A low-mileage replacement engine typically ranges from £3,000 to £6,000. Use our calculator for a figure specific to your car.

Is the Jaguar XJ 3.0 SC Petrol engine reliable?

The AJ126 supercharged V6 has a mixed reputation. It's a strong, smooth engine with excellent performance, but it has well-documented weaknesses: the water pump on pre-2015 models is 'poorly designed' and can fail catastrophically, the plastic cooling pipes are a known weak spot, and timing chain tensioners wear with age. Post-2015 models with the revised water pump are significantly more reliable.

What are the common problems with the Jaguar XJ 3.0 SC Petrol?

The main known issues are: (1) Water pump failure on pre-2015 models - can fail within 20,000 miles and destroy the engine if ignored, (2) Plastic coolant pipe ('V pipe') failure under the supercharger - a well-known weak spot, (3) Timing chain tensioner and guide wear - a design flaw shared with the 5.0 V8, (4) Valve cover gasket leaks and PCV diaphragm failure, and (5) Supercharger coupler wear causing rattling at idle.

Is it worth replacing a Jaguar XJ 3.0 SC Petrol engine, or should I scrap the car?

Depends on vehicle value and condition. Against a well-kept £8,000–£18,000 XJ, a £4,500–£7,500 recon is 25–90% of the car's value. For a clean, low-mileage example with good body and interior, replacement is often worth it given the XJ's rising classic status. However, if the car has other issues (air suspension, electrical faults, corrosion), evaluate total restoration costs before committing.

How do I find my Jaguar XJ 3.0 SC Petrol engine code?

The 3.0 SC uses the AJ126 (also known as 306PS) - a 3.0-litre supercharged V6 producing 340 bhp and 450 Nm. The engine code is stamped on the cylinder block. Tell us your registration and we'll confirm it for free.

Jaguar XJ 3.0 SC Petrol2010–20191 Engine Generation

Jaguar XJ 3.0 SC Petrol Engine Replacement - Compare Prices & Get Quotes

Name: Jaguar XJ 3.0 SC Petrol UK Engine Enquiry Data 2025
Creator: JaguarEngine.uk

Get quotes today from trusted UK Jaguar XJ specialists. The 3.0-litre AJ126 supercharged V6 delivers effortless performance with 340 bhp - compare reconditioned, rebuilt and used engines with supply & fit available nationwide.

Supply & Fit Available

12-Month Warranty

Nationwide Delivery

15 Specialists

Supply & Fit Available

12-Month Warranty

Nationwide Delivery

15 Specialists

Jaguar XJ 3.0 SC Petrol Engines - from £1,500 to £9,000Engine code: AJ126 (306PS)

Jaguar XJ 3.0 SC Petrol Engines - from £1,500 to £9,000· Engine code: AJ126 (306PS)

Instant QuotesNo Obligation100% FreeReconditionedRebuiltUsedSupply & Fit AvailableUK-Wide NetworkInstant QuotesNo Obligation100% FreeReconditionedRebuiltUsedSupply & Fit AvailableUK-Wide Network

Jaguar XJ 3.0 SC Petrol Which Engine Does Your Car Actually Have?

Four generations. Four eras. One guide to reliability, costs and what really matters.

Era Note

3.0L supercharged V6 - 340 bhp, 450 Nm. Water pump and plastic coolant pipe failures; timing chain tensioner wear on higher-mileage examples

GenerationYearsEngine CodeReliabilityRecon CostEra Note

2010–2019AJ126 (306PS)★★★☆☆ [NEWLY ASSIGNED - see Data Note]£4,500–£7,500 [JAG-QUOTE]3.0L supercharged V6 - 340 bhp, 450 Nm. Water pump and plastic coolant pipe failures; timing chain tensioner wear on higher-mileage examples

Why use this era map?

Every cost guide, reliability rating and engine code on this page is aligned to the data above. This keeps everything consistent and trustworthy.

Real UK Cost Data

Verified Reliability

Expert Insights

Updated for 2025

Jaguar XJ 3.0 SC Petrol Engine Replacement Costs

Supply Only£4,500–£7,500

Fitted (Indie)£6,500–£9,500

Warranty12–24 months

Best ForMost owners - best cost/warranty balance

Engine TypeSupply OnlyFitted (Indie)WarrantyBest For

Used Engine£1,500–£3,500£2,500–£5,0001–6 monthsBudget priority; lower-mileage donor

Reconditioned Engine£4,500–£7,500£6,500–£9,50012–24 monthsMost owners - best cost/warranty balance

Rebuilt Engine£5,500–£9,000£7,500–£11,00012–24 monthsLong-term ownership; 3+ year horizon

Main Dealer New£15,000–£30,000+£17,000–£32,000+24–36 monthsInsurance jobs, warranty claims

Labour estimate: Fitting an XJ 3.0 SC engine typically takes 14–18 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer). The supercharger and complex cooling system add labour time.

Compare XJ 3.0 SC Petrol engine prices from UK specialists

Common Problems

1. Water Pump Failure (Pre-2015 Models)

Symptoms: Low coolant warning light, coolant loss with no visible leak, overheating, coolant residue around the water pump pulley

Typical mileage: 20,000–60,000 miles - some fail within the first 20,000 miles

Repair cost: £400–£800 (water pump replacement; replace the small coolant pipe at the same time)

Replacement cost: N/A - repair only (does not progress to engine replacement if addressed)

🔴 Immediate - if the low coolant warning appears, pull over within seconds to avoid destroying the engine

Our recommendation:

Both the V8 and V6 engines were fitted with a poorly designed water pump until 2015. Coolant gets inside the bearing housing, corroding the water pump bearing and causing leaks. If you get a "low coolant" alert, stop driving immediately - continuing can destroy the engine. The obvious solution is to get the pump changed as soon as possible after buying the car, ideally to the later revised pump. Replace the small coolant pipe that connects to the pump at the same time.

Read the full water pump failure guide

1. Water Pump Failure (Pre-2015 Models)

Symptoms: Low coolant warning light, coolant loss with no visible leak, overheating, coolant residue around the water pump pulley

Typical mileage: 20,000–60,000 miles - some fail within the first 20,000 miles

Repair cost: £400–£800 (water pump replacement; replace the small coolant pipe at the same time)

Replacement cost: N/A - repair only (does not progress to engine replacement if addressed)

🔴 Immediate - if the low coolant warning appears, pull over within seconds to avoid destroying the engine

Our recommendation:

Read the full water pump failure guide

2. Plastic Coolant Pipe Failure ("V Pipe" Under Supercharger)

Symptoms: Overheating, coolant loss, steam from engine bay, bubbling in the coolant reservoir

Typical mileage: 40,000–80,000 miles

Repair cost: £600–£1,200 (plastic V pipe replacement with upgraded metal pipes)

Replacement cost: £5,500–£11,000 (if ignored - engine replacement)

🔴 Immediate - if the system dumps coolant, pull over immediately and don't restart

Our recommendation:

The plastic "V pipe" under the supercharger is a "well-known weak spot on these engines that often fails catastrophically". When it fails, the system dumps most of its coolant, pressurising and spraying everywhere. This can lead to cracked cylinder heads and a "new engine" scenario. Upgraded metal replacements are available. If you experience overheating or coolant loss, have the plastic cooling pipes inspected and replaced with metal versions as a preventative measure.

Read the full coolant pipe failure guide → /failures/aj126-coolant-pipe-failure/ [NEW FAILURE PAGE NEEDED]

3. Timing Chain Tensioner & Guide Wear

Symptoms: Rattling on cold start, restricted performance warning, engine warning light, metallic noise from the front of the engine

Typical mileage: 60,000–120,000 miles - more common on higher-mileage examples

Repair cost: £1,500–£3,500 (timing chain kit, tensioners and guides)

Replacement cost: £5,500–£11,000 (if chain jumps - full engine replacement)

🔴 Immediate - if you hear rattling on cold start, book an inspection today

Our recommendation:

The AJ126 supercharged 3.0 V6 has the "exact same tensioner/timing chain problems as the earlier AJ133 supercharged 5.0 V8". A design flaw in the tensioners and guides means the steel tensioner piston slowly wears away the aluminium guide button. If the chain jumps, pistons can hit valves. A £1,500–£3,500 preventative chain replacement is dramatically cheaper than a £5,500–£11,000 engine replacement.

Read the full timing chain failure guide → /failures/aj126-timing-chain/ [NEW FAILURE PAGE NEEDED]

4. Valve Cover Gasket & PCV Diaphragm Failures

Symptoms: Burning oil smell, visible oil leaks, oil consumption, lean running error codes

Typical mileage: 60,000–100,000 miles

Repair cost: £400–£800 (valve cover gasket replacement) / £200–£400 (PCV diaphragm replacement)

Replacement cost: N/A - repair only (does not progress to engine replacement if addressed)

🟡 Monitor - book inspection if you notice oil spots or burning smell

Our recommendation:

The 3.0 V6 gas engine has "coolant issues relating to the pipework and leaking valve cover gasket". Rubber PCV diaphragms rip with age, causing oil consumption and possible lean running error codes. Replacing PCV diaphragms is "a pain" with the supercharger on, so best done when the supercharger is off. If you notice a burning smell or oil spots, have the gaskets inspected promptly.

Read the full oil leak guide → /failures/valve-cover-gasket-leak/ [NEW FAILURE PAGE NEEDED]

Ready to Compare?

Get Matched With a Vetted Jaguar Specialist

15 vetted Jaguar specialists, every XJ 3.0 SC engine covered, with a 12-month warranty as standard.

Get My Free XJ Engine Quotes Now

XJ 3.0 SC Petrol Repair, Buy, or Replace?

Every 320d has a story. Make the right call with clear data, real-world costs, and honest guidance from UK specialists.

XJ 3.0 SC Petrol Repair, Buy, or Replace?

Every 320d has a story. Make the right call with clear data, real-world costs, and honest guidance from UK specialists.

Can It Be Repaired?

ProblemRepairable?Typical CostWhen It Makes SenseWater pump failure (pre-2015)✅ Yes£400–£800Essential preventative work - replace with revised pumpPlastic coolant V-pipe failure✅ Yes£600–£1,200Upgrade to metal pipes for permanent fixTiming chain rattle (early detection)✅ Yes£1,500–£3,500Preventative - catches the fault before catastrophic failureTiming chain jumped❌ Usually NoEngine replacementInterference engine - pistons hitting valves means full replacementValve cover gasket / PCV leaks✅ Yes£400–£800Catch early to prevent oil contamination

Buying This XJ 3.0 SC Petrol? Check These First

Buy If

Post-2015 model with revised water pump - this is the critical item
Documented cooling system overhaul (water pump, V-pipe with metal replacements)
Full service history with regular oil changes
No rattling on cold start - timing chain health is critical

Avoid If

Pre-2015 model with no water pump history - this is a ticking time bomb
Any coolant loss or overheating history
Rattling or ticking from the front of the engine - tensioner warning
Poor service history - the AJ126 is a complex engine that needs proper maintenance

Closing Verdict

The XJ 3.0 SC's AJ126 supercharged V6 is a genuinely impressive engine - 340 bhp and 450 Nm in a lightweight, elegant luxury saloon. It's effectively a 5.0-litre V8 with two cylinders removed, sharing much of its architecture with the larger engine. However, it has well-documented weaknesses: the pre-2015 water pump is notoriously unreliable, the plastic coolant pipes fail catastrophically, and the timing chain tensioners wear over time. Buy a post-2015 model with documented cooling system work, or budget for these repairs immediately. Without history? Proceed with extreme caution - the repair bills can be eye-watering.

Don't guess.Get the right engine at the right price.

Compare XJ 3.0 SC Petrol engine prices before you buy

Don't Guess. Compare.

Get real quotes from vetted UK specialists and make the right call for your 320d.

Compare XJ 3.0 SC Petrol engine prices before you buy

20+ Vetted Specialists UK Network

12-Month Warranty as Standard

Nationwide Delivery & Collection

Transparent Pricing, No Hidden Fees

Thousands of 320d Owners Helped

Buying Checklist

Before you buy a used Jaguar XJ 3.0 SC Petrol (or before you commit to an engine replacement), check these:

Water Pump History

Has it been replaced with the revised post-2015 pump? Pre-2015 pumps fail

Cooling System

Check for coolant leaks; have the plastic V-pipe been upgraded to metal?

Cold Start

Listen for rattling from the front of the engine (timing chain tensioner warning)

Coolant Level

Check for frequent top-ups; low coolant warnings are a critical red flag

Service History

Including the AJ126 engine and confirmed oil change intervals

Oil Leaks

Look for oil residue around the valve covers and PCV system

Supercharger Noise

Any rattling at idle? (Coupler wear)

Engine Warning Light

Have codes been read? Look for timing or cooling-related codes

Buy smart. Drive with confidence.

A few checks today can save thousands tomorrow. Use this checklist to avoid the most common 320d pitfalls.

Buy smart. Drive with confidence.

A few checks today can save thousands tomorrow. Use this checklist to avoid the most common 320d pitfalls.

Engine Codes

This table's rows match Section 1B's Era Map exactly.

AJ126 (306PS)

Years2010–2019

Power340 bhp (250 kW) / 450 Nm

2025 Enquiries- (pattern data)

Avg. Recon Cost£4,500–£7,500【JAG-QUOTE】

Engine CodeYearsPower2025 EnquiriesAvg. Recon Cost

AJ126 (306PS)2010–2019340 bhp (250 kW) / 450 Nm- (pattern data)£4,500–£7,500【JAG-QUOTE】

Technical Specs

AJ126 / 306PS

Displacement2,995 cc (3.0L)

Cylinders6-cylinder V

Bore84.5 mm / Stroke: 89.0 mm

Cylinder BlockAluminium

Cylinder HeadAluminium 24-valve DOHC

ValvetrainDOHC, 4 valves per cylinder, chain-driven

Compression Ratio10.5:1

Fuel SystemDirect injection (Supercharged MPFI)

SuperchargerRoots-type supercharger

Power250 kW (340 bhp) @ 6,500 rpm

Torque450 Nm @ 3,500 rpm

0-62 mph5.7 seconds

Top Speed155 mph (limited)

Engine Oil5W-30, 7.3 litres capacity

CO2 Emissions224 g/km

→ Compare XJ 3.0 SC Petrol engine prices for your Jaguar

Get quotes from trusted UK specialists in minutes.

Market Intelligence

Most Common Failure

Water pump failure (pre-2015 models)

can fail within 20,000 miles and destroy the engine if ignored

Average Enquiry Mileage

40,000

–80,000 miles【PATTERN DATA】

Average Replacement Cost

£4,500

–£7,500 reconditioned, supply only【JAG-QUOTE】

Most Requested Engine Code

AJ126 (306PS)【PATTERN DATA】

Peak Enquiry Season

Summer

cooling system issues become more apparent【PATTERN DATA】

Regional Demand

South East18%

London15%

South West (10%)【PATTERN DATA】

Regional Demand Breakdown

18%South East

15%London

Frequently Asked Questions

All prices are indicative UK market ranges based on historical quote data from our network of engine specialists. Actual costs vary by variant, engine code, damage severity and workshop location. Use our free comparison tool to get tailored quotes. Every engine supplied through EnginesMarket carries a minimum 12-month unlimited-mileage warranty - always confirm terms with your chosen supplier.

Why UK Jaguar XJ 3.0 SC Petrol Owners Trust JaguarEngine.uk

Trusted XJ 3.0 SC Engine Suppliers
every garage and engine rebuilder in our network is vetted, rated and reviewed by real XJ owners, across the AJ126 supercharged V6, as part of the Engine Finders network.
Compare XJ Engine Replacement Companies
see prices, warranty terms and supply & fit options side-by-side before you commit.
UK Engine Replacement Services for XJ 3.0 SC
supply-only or full supply & fit available nationwide, covering every X351 XJ 3.0 SC since 2010.

Find the best Jaguar XJ 3.0 SC Petrol engine replacement UK drivers rely on. Compare prices from trusted specialists on EnginesMarket today and get back on the road with confidence.

Compare Jaguar XJ 3.0 SC Petrol Engine Prices Now

100% Free

No hidden fees

No Obligation

Get quotes with zero pressure

UK Specialists

20+ vetted experts

12-Month Warranty

As standard

Nationwide Delivery

Supply & fit available

100% Free

No hidden fees

No Obligation

Get quotes with zero pressure

UK Specialists

20+ vetted experts

12-Month Warranty

As standard

Nationwide Delivery

Supply & fit available