How much does a BMW 1 Series 135i engine replacement cost in the UK?

A reconditioned N55 engine typically costs £4,000–£6,000 supply only, with the older N54 slightly lower. Fitting adds £1,000–£1,600. Use our calculator for a figure specific to your 135i.

Is the BMW 135i engine reliable?

It depends which engine your 135i has. The N54 (2008–2010) is immensely tunable but has well‑documented HPFP, injector, wastegate and carbon buildup issues. The N55 (2010–2013) is more robust with water pump and VANOS as the main watchpoints. Check the Era Map above for your specific car.

What are the common problems with the BMW 135i engine?

N54: HPFP failure, injector failure, wastegate rattle, carbon buildup. N55: water pump failure, VANOS issues, oil filter housing gasket leaks. Both are fundamentally strong but maintenance‑intensive.

Is it worth replacing a 135i engine, or should I scrap the car?

Depends on vehicle value. An E82 135i is a £5,000–£15,000 vehicle - a £4,000–£5,000 recon is 27–100% of the car's value. For lower‑value examples (sub‑£7,000), evaluate carefully against our 70% BMW scrap threshold. A well‑maintained, lower‑mileage example justifies replacement; a tired, high‑mileage one may not.

How do I find my BMW 135i engine code?

Listed on the VIN plate and vehicle documentation. The 135i covers N54 (2008–2010) and N55 (2010–2013). Tell us your registration date and we'll confirm which one you have for free.

Can I prevent the HPFP failure on a 135i?

On N54 cars, fitting the revised HPFP (BMW part number ending in -044) is the most effective prevention. Using high‑quality fuel and regular service can also help. If you experience long cranking, have the fuel pressure tested immediately.

BMW 1 Series 135i2008–2013N54 / N55

BMW 1 Series 135i Engine Replacement — Compare Prices & Get Quotes

The 135i badge covers two distinct twin-turbo/single-turbo straight-six engines - the high-boost N54 (2008–2010) and the more robust N55 (2010–2013). Get quotes from trusted UK specialists today.

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1 Series 135i Engines - from £2,000 to £8,000N54 / N55

1 Series 135i Engines - from £2,000 to £8,000· N54 / N55

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The 135i 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?

This table is the single source every other section on this page matches - Sections 2, 4 and 6 reference it rather than restating conflicting figures.

Real UK Cost Data

Verified Reliability

Expert Insights

Updated for 2025

BMW 1 Series 135i Engine Replacement Costs

Supply Only£3,500–£6,000

Fitted (Indie)£4,700–£7,400

Warranty12–24 months

Best ForMost owners - best cost/warranty balance

Engine TypeSupply OnlyFitted (Indie)WarrantyBest For

Used Engine£2,000–£3,500£3,000–£4,8001–6 monthsBudget priority; vehicle under £5,000

Reconditioned Engine£3,500–£6,000£4,700–£7,40012–24 monthsMost owners - best cost/warranty balance

Rebuilt Engine£5,500–£8,000£6,700–£9,40012–24 monthsLong-term ownership; 3+ year horizon

Main Dealer New£8,000–£12,000£9,200–£13,60024–36 monthsInsurance jobs, warranty claims

Figures above reflect both engine eras; N54-era pricing runs slightly lower than N55 - see the Era Map above.

Labour estimate: Fitting a 1 Series 135i engine typically takes 12–16 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer).

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Common Problems With BMW 320d Engines

1. High‑Pressure Fuel Pump Failure (N54, 2008–2010)

Symptoms: Long crank on start, rough idle, loss of power, engine stalling, engine warning light, reduced performance under load.

Typical mileage: 40,000–80,000 miles

Repair cost: £600–£1,200 (HPFP replacement) [PLACEHOLDER - confirm vs cost sheet]

Replacement cost: N/A - repair only (unless injectors also damaged)

🟠 Check - book inspection urgently if symptoms appear

Our recommendation:

The N54's HPFP is its defining weakness - a well-documented issue that plagued early cars. If you experience long cranking or loss of power, have the fuel pressure tested. BMW issued recalls for this, but many cars are now out of warranty. Replacing the HPFP with a revised unit is the permanent fix.

1. High‑Pressure Fuel Pump Failure (N54, 2008–2010)

Symptoms: Long crank on start, rough idle, loss of power, engine stalling, engine warning light, reduced performance under load.

Typical mileage: 40,000–80,000 miles

Repair cost: £600–£1,200 (HPFP replacement) [PLACEHOLDER - confirm vs cost sheet]

Replacement cost: N/A - repair only (unless injectors also damaged)

🟠 Check - book inspection urgently if symptoms appear

Our recommendation:

2. Injector Failure (N54, 2008–2010)

Symptoms: Rough idle, misfire, fuel smell from exhaust, increased fuel consumption, engine warning light.

Typical mileage: 40,000–80,000 miles

Repair cost: £600–£1,500 (injector set replacement) [PLACEHOLDER - confirm vs cost sheet]

Replacement cost: N/A - repair only

🟠 Check - book inspection urgently if symptoms appear

Our recommendation:

N54 injectors are another well-known weak point - they can leak or fail, causing misfires and fuel contamination. BMW issued revised injectors (index 12) which are more reliable. If you experience rough running, have the injectors tested - replacing them as a set is recommended.

3. Water Pump Failure (N55, 2010–2013; also affects N54)

Symptoms: Coolant loss, temperature fluctuations, engine warning light, heater not working properly, overheating.

Typical mileage: 50,000–90,000 miles

Repair cost: £500–£1,000 (electric water pump replacement) [PLACEHOLDER - confirm vs cost sheet]

Replacement cost: N/A - repair only

🟡 Monitor - book inspection soon

Our recommendation:

Both N54 and N55 use electric water pumps, which have a finite life. If you notice temperature fluctuations or coolant loss, have the cooling system inspected. Replacing the water pump preventatively at 60,000–80,000 miles is recommended by specialists.

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135i - 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.

135i - 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 SenseHPFP failure (N54)✅ Yes£600–£1,200Straightforward - replace with revised unitInjector failure (N54)✅ Yes£600–£1,500Replace as a set - use index 12 revised injectorsWater pump failure (N54/N55)✅ Yes£500–£1,000Routine maintenance - do preventativelyWastegate rattle (N54)⚠️ Sometimes£1,500–£3,000Often requires turbo replacement; consider overall engine healthSevere engine damage (chain snap / overheating)❌ Usually NoEngine replacementLittle left to salvage - replacement is the only option

Buying This 135i? Check These First

Buy If

N54 (2008–2010): HPFP replaced with revised unit (or documented recall)
N54: injectors replaced with index 12 revised units
Both: water pump replaced preventatively
Full service history with BMW-spec oil and regular intervals

Avoid If

Long cranking on N54 - HPFP may be failing
Rough idle on N54 - injectors may be leaking
Temperature fluctuations - water pump may be failing
Engine warning light with no diagnosis - potentially expensive issue

Closing Verdict

The 135i is one of BMW's most characterful performance cars - a small, rear‑wheel‑drive coupé with a legendary straight‑six. The N54 is the more tunable but less reliable engine; the N55 is the more robust choice. Both are maintenance‑intensive, so buy on documented history with key items (HPFP, injectors, water pump) replaced. A well‑maintained 135i is a future classic; a neglected one is a £4,000+ repair bill waiting to happen.

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

→ Compare 135i engine prices before you buy

Don't Guess. Compare.

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Buying Checklist

Before you buy a used BMW 1 Series 135i (or before you commit to an engine replacement), check these:

Cold Start

Listen for smooth start; long cranking indicates HPFP issues (N54)

Rough Idle

Check for misfire or uneven running; injector failure indicator (N54)

Service History

including which engine era (N54 or N55) and confirmed maintenance

Water Pump

Check for temperature fluctuations; common failure on both

Wastegate Rattle

Listen for rattling on deceleration (N54); may indicate turbo wear

Oil Consumption

Does it use more than 1L per 1,000 miles?

Engine Warning Light

Have codes been read? Any unresolved issues?

MOT History

Check for emissions‑related failures

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.

BMW 320d Engine Codes

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

N54 (3.0 twin-turbo straight-six)

Years2008–2010

Power306 PS (302 bhp) @ 5,800 rpm; 400 Nm @ 1,300–5,000 rpm

2025 Enquiries- (pattern data)

Avg. Recon Cost£3,500–£5,500 [PLACEHOLDER]

Engine CodeYearsPower2025 EnquiriesAvg. Recon Cost

N54 (3.0 twin-turbo straight-six)2008–2010306 PS (302 bhp) @ 5,800 rpm; 400 Nm @ 1,300–5,000 rpm- (pattern data)£3,500–£5,500 [PLACEHOLDER]

N55 (3.0 single-turbo straight-six)2010–2013306 PS (302 bhp) @ 5,800 rpm; 400 Nm @ 1,200–5,000 rpm- (pattern data)£4,000–£6,000 [PLACEHOLDER]

Technical Specs

N55 3.0 single-turbo straight-six

Displacement2,979 cc

Cylinders6-cylinder inline (straight-six)

Compression Ratio10.2:1

Fuel SystemDirect injection

TurbochargerSingle-twin-scroll turbocharger

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Market Intelligence

Most Common Failure

N54: HPFP / injector failure; N55: water pump failure

[PATTERN DATA]

Average Enquiry Mileage

70,000

miles

[PATTERN DATA]

Average Replacement Cost

£4,500

reconditioned, supply only

[PLACEHOLDER - confirm vs cost sheet]

Most Requested Engine Code

N54 (approximately 60% of 135i enquiries)

[PATTERN DATA]

Peak Enquiry Season

Autumn/Winter

cold starts expose HPFP and water pump issues

[PATTERN DATA]

Regional Demand

London18%

South East17%

North West13%

PATTERN DATA

Regional Demand Breakdown

18%London

17%South East

13%North West

BMW 320d - 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.

Find the best BMW 1 Series 135i engine replacement UK drivers rely on. Compare prices from trusted specialists on EnginesMarket today and get back on the road with confidence - from £2,000 for a used unit to £8,000 for a fully rebuilt straight‑six.

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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