How much does a Mercedes-AMG A45 engine replacement cost in the UK?

A reconditioned M133 engine typically costs £3,500–£7,500 supply only; a reconditioned M139 costs £5,000–£12,000. Used units are available from £2,000–£4,500. Fitting adds £1,500–£2,500. W176 A45 engine replacement costs are 'into five figures'. Use our calculator for a figure specific to your A45.

Is the Mercedes-AMG A45 engine reliable?

The A45's engines are highly-strung performance units — they produce over 190 hp per litre. Reliability depends entirely on maintenance history. Known issues include timing chain stretch, HPFP failure, turbo oil feed problems (early 2014 cars), and carbon build-up (M139). With 10,000-mile service intervals and 98/99 RON fuel, they can be reliable.

What are the common problems with the Mercedes-AMG A45?

Timing chain stretch and guide wear (the most critical issue), high-pressure fuel pump failure (power loss under load), turbocharger oil feed issues (early 2014 cars — subject to recall), carbon build-up on intake valves (M139), cooling system leaks (water pump and thermostat housing), and 7-speed DCT gearbox issues.

Is it worth replacing a Mercedes-AMG A45 engine, or should I scrap the car?

A45 values remain strong — a well-kept W176 is often worth £12,000–£25,000, while W177 cars fetch £25,000–£45,000+. A £3,500–£12,000 reconditioned engine is 15–40% of the vehicle's value — apply the Mercedes 70% scrap threshold. If the car is a cherished example, replacement is often worthwhile.

How do I find my Mercedes-AMG A45 engine code?

Listed on the VIN plate and vehicle documentation. W176 A45 (2013–2018) uses M133; W177 A45 (2019+) uses M139. Tell us your registration date and we'll confirm it for free.

Can I repair the M133/M139 timing chain, or does the engine need replacement?

The timing chain and tensioner can be replaced preventatively — they are wear items. Replacement costs £1,500–£3,500. If the chain fails and jumps timing, the engine is typically destroyed. A preventative tensioner replacement is far cheaper than a full engine replacement (£3,500+). At the first sign of rattling from the front of the engine, book an inspection immediately.

Mercedes-AMG A452013–present2 Engine Generations

Mercedes-AMG A45 Engine Replacement — Compare Prices & Get Quotes

Name: Mercedes-AMG A45 UK Engine Enquiry Data 2025
Creator: MercedesEngine.uk

The A45 AMG is powered by the world's most powerful production four-cylinder engines — the M133 in the original and the hand-built M139 in the current car. Both deliver astonishing performance, but timing chain stretch, turbo oil feed issues and high-pressure fuel pump failures are well-documented. Get quotes from UK specialists for reconditioned, rebuilt and used units today.

Supply & Fit Available

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Mercedes-AMG A45 Engines — from £2,000 to £12,000Common codes: M133, M139

Mercedes-AMG A45 Engines — from £2,000 to £12,000· Common codes: M133, M139

Instant QuotesNo Obligation100% FreeReconditionedRebuiltUsedSupply & Fit AvailableUK-Wide Network

The A45 AMG THROUGH TIME — Era Map

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

GenerationYearsEngine CodeReliabilityRecon CostEra Note

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

Mercedes-AMG A45 Engine Replacement Costs

Supply Only£3,500–£7,500

Fitted (Indie)£5,500–£9,500

Warranty12–24 months

Best ForMost owners — best cost/warranty balance

Engine TypeSupply OnlyFitted (Indie)WarrantyBest For

Used Engine£2,000–£4,500£4,000–£6,5001–6 monthsBudget priority; lower‑mileage examples

Reconditioned Engine£3,500–£7,500£5,500–£9,50012–24 monthsMost owners — best cost/warranty balance

Rebuilt Engine£6,000–£12,000£8,000–£14,00012–24 monthsLong‑term ownership; 3+ year horizon

Main Dealer New£10,000–£15,000+£12,000–£18,000+24–36 monthsInsurance jobs, warranty claims

Figures above reflect the current A45 AMG market. W176 M133 engines sit at the lower end of the range; W177 M139 engines command a premium. W176 A45 engine replacement costs are "into five figures". Reconditioned M139 units are significantly more expensive due to their complexity and hand-built nature.

Labour estimate: Fitting an A45 AMG engine typically takes 12–16 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer). The transverse layout and complex turbo/ancillary packaging make it a specialist job.

→ Compare A45 AMG engine prices from UK specialists

Common Problems

1. Timing Chain Stretch and Guide Wear (M133 and M139)

Symptoms: Rattling noise on cold start, metallic ticking from the front of the engine, delayed starting, engine warning light, cam timing errors, "check engine" light

Typical mileage: 60,000–100,000 miles

Repair cost: £1,500–£3,500 (timing chain, tensioner and guide replacement)

Replacement cost: £3,500–£7,500 (if chain jumps and causes valve interference)

🔴 Immediate - if the timing chain fails, the engine is typically destroyed

Our recommendation:

The M133 and M139 engines are highly strung, producing over 190 hp per litre. This puts immense strain on the timing chain and tensioner system. One W176 A45 owner reported a timing chain that had "stretched and guides worn, cams misalignment and high pressure petrol pump faulty" — the whole cost was "equating to replacement engine". If you hear rattling on cold start, book an inspection immediately. Preventative timing chain replacement is far cheaper than a full engine replacement. Regular oil changes (every 10,000 miles) are essential.

Read the full timing chain failure guide

1. Timing Chain Stretch and Guide Wear (M133 and M139)

Symptoms: Rattling noise on cold start, metallic ticking from the front of the engine, delayed starting, engine warning light, cam timing errors, "check engine" light

Typical mileage: 60,000–100,000 miles

Repair cost: £1,500–£3,500 (timing chain, tensioner and guide replacement)

Replacement cost: £3,500–£7,500 (if chain jumps and causes valve interference)

🔴 Immediate - if the timing chain fails, the engine is typically destroyed

Our recommendation:

Read the full timing chain failure guide

2. High-Pressure Fuel Pump (HPFP) Failure (M133 and M139)

Symptoms: Sudden loss of power under load (uphill or overtaking), check engine light, normal operation after restart, rough idle, over-fuelling

Typical mileage: 40,000–80,000 miles

Repair cost: £800–£2,000 (HPFP replacement)

Replacement cost: £3,500–£7,500 (if pump failure causes engine damage)

🟠 Check - book inspection urgently

Our recommendation:

High-pressure fuel pump failure is a well-documented issue on both M133 and M139 engines. One owner had their dealership replace both low-pressure and high-pressure pumps, only for the new high-pressure pump to fail again. Symptoms include sudden power loss under load and a check engine light that clears after a restart. If you experience any hesitation or power loss, have the fuel system inspected. Using high-quality fuel (98/99 RON) is essential — the A45 "runs like a pig on 95".

Read the full fuel pump failure guide

3. Turbocharger Oil Feed Issues (Early M133 — 2014)

Symptoms: Whistling or grinding noise from the turbo, loss of power, excessive smoke, turbo wear

Typical mileage: 30,000–60,000 miles

Repair cost: £1,500–£3,500 (turbocharger replacement)

Replacement cost: £3,500–£7,500 (if turbo failure causes engine damage)

🔴 Immediate - early 2014 A45s suffered from oil feed issues to the turbocharger

Our recommendation:

Early 2014 A45s suffered from a design flaw where the turbocharger lacked an anti-surge valve. Pressure could only escape through the turbo impeller, causing it to wear. Mercedes issued a recall to address this, so check if the work has been done. If you notice any whistling, grinding or loss of power from the turbo, have it inspected immediately. A failing turbo can send debris through the engine, destroying it.

Read the full turbocharger failure guide

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A45 AMG — 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.

A45 AMG — 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 SenseTiming chain tensioner (preventative)✅ Yes£1,500–£3,500Labour-intensive but far cheaper than a full engine replacementTiming chain failure (engine damage)❌ Usually NoEngine replacementIf chain jumps and valves hit pistons, replacement is the only optionHPFP failure✅ Yes£800–£2,000Replacement — catch before engine damageTurbo oil feed issue (2014 recall)✅ YesFree (under recall)Check if recall has been completedCarbon build-up (M139)✅ Yes£500–£1,200Walnut blasting — well-understood by AMG specialistsCooling system leaks✅ Yes£400–£1,200Water pump and thermostat housing are known failure points

Buying This A45 AMG? Check These First

Buy If

2016+ facelift W176 — later cars have improved turbo components and revised gearbox ratios
W177 with comprehensive warranty — M139 engines are complex and expensive to repair
Evidence of 10,000-mile service intervals — essential for these highly-strung engines
Turbo recall work completed on early 2014 cars — check the service history
Full service history with correct 98/99 RON fuel used

Avoid If

Any rattling from the front of the engine — timing chain wear is likely
Early 2014 car with no proof of turbo recall work — oil feed issues are a known risk
Evidence of repeated HPFP failures — suggests a deeper fuel system issue
Poor service history — these engines are unforgiving of long oil change intervals
Any "check engine" light without a clear diagnosis

Closing Verdict

The A45 AMG is a genuine performance icon — the world's most powerful production four-cylinder in its day, and still one of the most exciting hot hatches ever built. But these are highly-strung engines that demand meticulous maintenance. Timing chain wear, HPFP failures, and turbo oil feed issues (on early cars) are well-documented. Buy on history, maintain religiously with 10,000-mile service intervals, and use 98/99 RON fuel. Skip the maintenance and it will punish you.

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

→ Compare A45 AMG 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 A45 AMG engine prices before you buy

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Buying Checklist

Before you buy a used Mercedes-AMG A45 (or before you commit to an engine replacement), check these:

1. Cold Start — Listen for rattles from the front of the engine (timing chain tensioner warning)

2. Service History — including which generation (W176 or W177) and evidence of 10,000-mile service intervals

3. Turbo Recall (2014) — Has the turbo oil feed recall been completed?

4. Fuel System — Any history of power loss under load or HPFP replacement?

5. Coolant Level — Any unexplained loss? (water pump or thermostat housing warning)

6. Gearbox — Any crunching in reverse or jerky downshifts? (7-speed DCT can be problematic)

7. Engine Warning Light — Have codes been read? Any unresolved issues?

8. Fuel Type — Has the car been run on 98/99 RON? (95 RON causes poor running)

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 — two engine families across the A45 AMG's history.

M133

Years2013–2018

Power355–381 PS

2025 Enquiries[PATTERN DATA]

Avg. Recon Cost£3,500–£7,500 [MB-QUOTE]

Engine CodeYearsPower2025 EnquiriesAvg. Recon Cost

M1332013–2018355–381 PS[PATTERN DATA]£3,500–£7,500 [MB-QUOTE]

M1392019–present382–421 PS[PATTERN DATA]£5,000–£12,000 [MB-QUOTE]

Technical Specs

M139 — current generation

Displacement1,991cc (2.0‑litre)

Cylinders4-cylinder inline

Compression Ratio9.0:1

Fuel SystemDirect injection

TurbochargerSingle twin-scroll turbocharger (reverse-mounted)

ValvetrainDOHC, 4 valves per cylinder, timing chain

ConstructionHand-built "one man, one engine"

→ Compare A45 AMG engine prices for your Mercedes

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Market Intelligence

Most Common Failure

Timing chain stretch and guide wear — the defining risk on both M133 and M139 engines

Average Enquiry Mileage

50,000

–90,000 miles【PATTERN DATA】

Average Replacement Cost

£3,500

–£12,000 reconditioned, supply only depending on generation【MB-QUOTE】

Most Requested Engine Code

M133 — the original A45 AMG engine【PATTERN DATA】

Peak Enquiry Season

Spring — performance car season【PATTERN DATA】

Regional Demand

London22%

South East18%

South West (14%)【PATTERN DATA】

Regional Demand Breakdown

22%London

18%South East

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.

Trusted A45 Engine Suppliers
every garage and engine rebuilder in our network is vetted, rated and reviewed by real A45 AMG owners, as part of the Engine Finders network, across both the M133 and M139 generations — no matter which A45 era you drive.
Compare A45 Engine Replacement Companies
see prices, warranty terms and supply & fit options side‑by‑side before you commit, with specialists who genuinely understand the M133/M139's timing chain, HPFP, and turbo nuances.
UK Engine Replacement Services for A45 AMG
supply‑only or full supply & fit available nationwide, covering Mercedes-AMG's most powerful four-cylinders with a 12‑month warranty as standard.

Find the best Mercedes-AMG A45 engine replacement UK drivers rely on. Compare prices from trusted specialists on MercedesEngine.uk today and keep your AMG performing at its best.

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12-Month Warranty

As standard

Nationwide Delivery

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