Car Model Guide/ BMW/ 1 Series/ E88/ 135i
BMW·1 Series·E88 convertible

135i N54 / N55

Sold with 2 different engines in this chassis, N54 2008–2010, N55 2010–2013. Both are on this page; they differ in exactly the ways that cost money.

Overview

The 135i is the N54 petrol version of the BMW 1 Series convertible (E88), sold 2008–2010 with 306 PS and manual or automatic. High risk at level 4. The twin-turbo fuel system, turbos and cooling all fail on schedule and each repair runs into four figures. 22 failure modes are recorded against its engine, gearbox, chassis and shared components. Prices on this page are illustrative placeholders rather than a sourced market sample. See the methodology for how the bands are derived.

BMW 1 Series convertible (E88)

BMW 1 Series convertible (E88) · photo 2008-2010 BMW 120i (E88) convertible (2010-05-19) 01 by OSX · Public domain · Wikimedia Commons

Power306 PS
Torque400 Nm
Years2008–2013
Fuelpetrol
DriveRWD
EnginesN54 / N55
135i N54 · biggest risks

Ranked by probability × repair cost. 22 recorded in total.

41Fragile
  1. Fuel injector failure€1,800–€3,000partly checkable
  2. Turbocharger wastegate rattle and turbo failure€1,200–€3,500checkable
  3. "Lifetime" fluid neglect€400–€2,500partly checkable

Risk level −33 · Likely spend vs price −26 · all issues →

135i N55 · biggest risks

Ranked by probability × repair cost. 18 recorded in total.

52Demands diligence
  1. Dual-mass flywheel and clutch wear€900–€1,600checkable
  2. Carbon buildup on intake valves€400–€700not checkable
  3. Convertible roof drain blockage and motor water damage€200–€1,500partly checkable

Risk level −22 · Likely spend vs price −26 · all issues →

135i N54 · system by system9 systems reviewed · 1 with no recurring fault reported
EnginewatchOil filter housing gasket leak, €300–€600.
Fuel system⚠ attentionFuel injector failure, €1,800–€3,000.+1 more in this system
Turbo & intake⚠ attentionTurbocharger wastegate rattle and turbo failure, €1,200–€3,500.+2 more in this system
CoolingwatchElectric water pump and thermostat failure, €500–€800.+1 more in this system
Emissions✓ clearNo recurring fault reported for this system on this engine.
Transmission⚠ attention"Lifetime" fluid neglect, €400–€2,500.+3 more in this system
Electrics⚠ attentionConvertible roof drain blockage and motor water damage, €200–€1,500.+4 more in this system
Suspension & brakeswatchFront control arm bushing wear, €300–€700.+3 more in this system
Body & interiorwatchCorrosion at the rear subframe and arch seams, €300–€2,000.
135i N55 · system by system9 systems reviewed · 2 with no recurring fault reported
EnginewatchValve cover and PCV failure, €400–€700.+2 more in this system
Fuel system✓ clearNo recurring fault reported for this system on this engine.
Intake & airwatchCarbon buildup on intake valves, €400–€700.
CoolingwatchElectric water pump and thermostat failure, €500–€800.+1 more in this system
Emissions✓ clearNo recurring fault reported for this system on this engine.
Transmission⚠ attentionDual-mass flywheel and clutch wear, €900–€1,600.+1 more in this system
Electrics⚠ attentionConvertible roof drain blockage and motor water damage, €200–€1,500.+4 more in this system
Suspension & brakeswatchFront control arm bushing wear, €300–€700.+3 more in this system
Body & interiorwatchCorrosion at the rear subframe and arch seams, €300–€2,000.

Which engine

EngineYearsFaceliftPowerTorqueRiskIssuesGood buyIn one line
N542008–2010pre306 PS400 NmR422€10,350The cheap fast one, and cheap because the fuel pump, injectors, turbos and cooling all cost real money.
N552010–2013both306 PS400 NmR318€13,300The N54's fix: same 306 PS, one turbo, no fuel-pump epidemic. The 135i to buy.
Engine N54

135i N54B30 2008–2010

BMW's first modern turbo six. Strong bottom end, huge tuning headroom, and a fuel and boost system that bills you in €800 increments forever.

CautionGood buy at€10,350€8,250 – €18,900
R4 High risk22 issues

Risk 4, High risk. The twin-turbo fuel system, turbos and cooling all fail on schedule and each repair runs into four figures.

Known issues, ranked by expected cost

Faults recorded against this engine, its components and its chassis, ranked by likelihood × repair cost. Costs are indicative ranges with a stated labour basis.

Fuel injector failureN54B30€1,800–€3,000
Rough idle, cold-start stumble, misfire counts on one or two cylinders, occasional fuel smell. Piezo injectors leak or lose spray pattern. BMW revised the design repeatedly. The index number on the injector tells you which generation is fitted.
Check: Scan for per-cylinder misfire counts on a warm engine. It is the only honest check. Ask which injector index is fitted. Assume a car with no injector history will need some.
FuelcommonPartly detectableevidence: manufacturer80–180k km
Turbocharger wastegate rattle and turbo failureN54B30€1,200–€3,500
Metallic rattle on light throttle at low revs, later boost faults, underboost codes and power loss. Wastegate arm bushings wear and the flapper rattles in its seat. The turbos themselves are otherwise reasonably durable.
Check: Listen at cold idle and at light part throttle from 1,500–2,500 rpm. Rattle alone isn't fatal, cars run for years with it, but it should price the car.
Turbo & intakecommonDetectable at viewingevidence: documented120–220k km
"Lifetime" fluid neglectZF 6HP19 / 6HP21 six-speed automatic€400–€2,500
Harsh or hunting shifts, a shunt between second and third, delayed engagement when cold. BMW declared the fluid a lifetime fill. It's not. Fluid degrades, the valve body wears, and the box eventually fails.
Check: Drive it from cold through every gear, then in manual mode. Ask when the fluid was last changed. "It's sealed for life" means never, and you should price a service in.
TransmissioncommonPartly detectableevidence: documented120–200k km
Dual-mass flywheel and clutch wearGetrag six-speed manual€900–€1,600
Rattle at idle with the clutch up that disappears when you press it, judder on pull-away, gearbox rumble. The dual-mass flywheel's springs wear. Diesels and tuned petrols wear them faster.
Check: Idle in neutral with the clutch up and listen, then press the clutch. A rattle that stops when you press is the flywheel. Also check for judder pulling away in first.
TransmissioncommonDetectable at viewingevidence: documented130–250k km
Carbon buildup on intake valvesdirect injection€400–€700
Rough cold idle, slow throttle response, misfires, gradual loss of low-end response. Direct injection puts no fuel over the intake valves, so crankcase vapour deposits bake on undisturbed.
Check: Not visible without a borescope. Treat it as a service item that's due unless there's a receipt. It's not a fault, it's an unbudgeted maintenance cost.
Turbo & intakeuniversalNot detectable at viewingevidence: documented80–120k km
High-pressure fuel pump failureN54B30€700–€1,100
Long crank, extended cranking when warm, limp mode, misfire and hesitation under load. The direct-injection high-pressure pump loses delivery pressure and eventually fails outright. Early pumps went through several revisions.
Check: Insist on a cold start. Scan for fuel-pressure and misfire codes, and ask for a pump receipt with the part number. Revised part numbers appeared from 2010, so check the number rather than the build year.
Later parts: Revised pump part numbers from 2010 onward; not all cars received one.
FuelcommonPartly detectableevidence: manufacturer90–160k km
Convertible roof drain blockage and motor water damageE88 body€200–€1,500
Water on the seats or carpet and a damp boot, and, the expensive outcome, a roof that won't operate after the electro-hydraulic motor or sensor module is water-damaged. Blocked drain channels and perished seals let water pool in the boot well, where the roof motor and parking-sensor module sit. A soaked motor is the four-figure consequence.
Check: Fully open and close the roof, listening for the pump straining; lift the boot side-trims and feel for damp around the roof motor, and check the seals for shrinkage.
ElectricalcommonPartly detectableevidence: documented50–160k km
Front control arm bushing wearE9x chassis€300–€700
Knocking over bad surfaces, vague or wandering steering, uneven front tyre wear, steering shimmy under braking. The front lower arm bushings are a known wear item on this chassis and go well before the ball joints.
Check: Drive over a rough road at low speed with the windows down and listen. Check the inside edges of the front tyres for feathering.
SuspensionuniversalDetectable at viewingevidence: documented80–150k km

Ranked by probability × repair cost, not by how loudly a failure is discussed. Inherited from the engine, gearbox, chassis and shared components, each written once. All 22 issues in full →

Pre-purchase inspection

The same issue records, reordered into the sequence you can actually check them in: cold start, static, drive, paperwork.

22 checks · saved in this browser ·

1Cold startYou get one. If the engine is warm when you arrive, come back another day.

2Static checksEngine off, ideally on a lift.

3On the driveInclude low-speed manoeuvring, not just an open road.

4PaperworkOn these cars the folder is most of the value.

5OBD scanMandatory. A seller who refuses a scan has answered the question.

Mileage and servicing

What the odometer does and doesn't tell you here, plus the service items whose neglect causes the expensive failures above.

Service history and a receipts folder matter more than the odometer. So assume anything undocumented is due.

Service itemIntervalCost
High-pressure fuel pump
A known N54 failure, often under extended warranty in the US only
as it fails€700–1,100
Walnut-blast intake
Direct injection carbons the valves
roughly 100,000 km€300–500
Cooling system
Plastic tank, pump and thermostat are wear items
roughly 120,000 km€600–1,200

What to pay

What this engine sells for, against the median of every engine in the chassis. All figures are illustrative placeholders. See the basis chips.

Enter an asking price to get a verdict against this variant's band: cheap, fair, good buy or overpriced.

United States vs Europe

1 EUR = 1.08 USD ·
🇪🇺 Europe · EUR€10,350band €8,250–€18,900
🇺🇸 United StatesNot sold135i N54 was never a US-market car
What that meansNo US band exists to compare. Any car you find there's a private import, parts and specialist knowledge are thinner, and the price says more about import cost than about the market.

US figures are the EU band converted at a stated rate. No US market differential is modelled: we hold no sourced US asking prices, and inventing one would be worse than saying so. What the comparison does show for real is availability. Most of this range was never sold in the US.

  • ModelBMW 1 Series 135i
  • ChassisE88
  • EngineN54
  • Years2008–2010
  • MarketCentral EU
  • Windowrolling 12 months to 2026-07
€10k€15kE88 median, all 8 engines €7,800Pre-faceliftPre-facelift: low €8,250, good buy €10,350, average €12,400, high €18,900€12,400€8,250€18,900€10,350
Good buy at or under the marker · Median asking price · bar spans the 10th to 90th percentile · dashed line is the e88 median, all 8 engines

Good buy isn't the same as cheapest. The good-buy figure assumes the known failure items are either done with receipts or verifiably not yet due. Full breakdown by facelift phase →

Buyer notes

Our judgement, kept separate from the records it's built on.

Our read, not a record
The N54 135i is a 306 PS twin-turbo six for hot-hatch money, and the price reflects what it costs to keep. The high-pressure fuel pump, the piezo injectors, the wastegate rattle and the plastic cooling parts are all known, all recurring and all expensive. A car with a thick folder of recent work is a bargain; one without is a project. If you want the pace with less financial drama, the later N55 is worth the premium. Roughly the cost of one N54 repair.

Everything above this line comes from the issue and specification records. This paragraph is our judgement on top of them. See how we reach it.

Full specification

Manufacturer figures for this engine and body, as recorded in the variant and engine data.

Engine codeN54B30
ConfigurationI6, twin-turbo · 2979 cc
Fuel / injectionpetrol · direct
Model years2008–2010
Facelift phasePre-facelift only, to 2010
Power / torque306 PS · 400 Nm
Transmissions6-speed manual · 6-speed automatic (ZF)
Gearbox familiesGetrag six-speed manual · ZF 6HP19 / 6HP21 six-speed automatic
DrivetrainRWD
Economy (real-world)9.5–12 l/100 km mixed
MarketsEU
Engine N55

135i N55B30 2010–2013

The N54's replacement and the fix for most of its faults. Same output, one turbo, no fuel-pump epidemic. The obvious answer if the budget stretches.

Buy with conditionsGood buy at€13,300€10,600 – €25,700
R3 Demands diligence18 issues

Risk 3, Demands diligence. Fewer fuel-system faults than the N54, but the direct injection, cooling and DCT service still cost money.

Pre-facelift or facelift, this engine spans both

The same badge either side of the changeover. Bands are split at the facelift year from the generation record.

PhaseYearsLowAverageHighGood buyWhat differs
pre Pre-facelift2010€10,600€15,950€23,600€13,300The specification the car launched with.
LCI Facelift (LCI)2011–2013€11,600€17,350€25,700€14,500N55 replaced the N54 in the 135i; Revised lights, bumpers and interior

Known issues, ranked by expected cost

Faults recorded against this engine, its components and its chassis, ranked by likelihood × repair cost. Costs are indicative ranges with a stated labour basis.

Dual-mass flywheel and clutch wearGetrag six-speed manual€900–€1,600
Rattle at idle with the clutch up that disappears when you press it, judder on pull-away, gearbox rumble. The dual-mass flywheel's springs wear. Diesels and tuned petrols wear them faster.
Check: Idle in neutral with the clutch up and listen, then press the clutch. A rattle that stops when you press is the flywheel. Also check for judder pulling away in first.
TransmissioncommonDetectable at viewingevidence: documented130–250k km
Carbon buildup on intake valvesdirect injection€400–€700
Rough cold idle, slow throttle response, misfires, gradual loss of low-end response. Direct injection puts no fuel over the intake valves, so crankcase vapour deposits bake on undisturbed.
Check: Not visible without a borescope. Treat it as a service item that's due unless there's a receipt. It's not a fault, it's an unbudgeted maintenance cost.
Turbo & intakeuniversalNot detectable at viewingevidence: documented80–120k km
Convertible roof drain blockage and motor water damageE88 body€200–€1,500
Water on the seats or carpet and a damp boot, and, the expensive outcome, a roof that won't operate after the electro-hydraulic motor or sensor module is water-damaged. Blocked drain channels and perished seals let water pool in the boot well, where the roof motor and parking-sensor module sit. A soaked motor is the four-figure consequence.
Check: Fully open and close the roof, listening for the pump straining; lift the boot side-trims and feel for damp around the roof motor, and check the seals for shrinkage.
ElectricalcommonPartly detectableevidence: documented50–160k km
Front control arm bushing wearE9x chassis€300–€700
Knocking over bad surfaces, vague or wandering steering, uneven front tyre wear, steering shimmy under braking. The front lower arm bushings are a known wear item on this chassis and go well before the ball joints.
Check: Drive over a rough road at low speed with the windows down and listen. Check the inside edges of the front tyres for feathering.
SuspensionuniversalDetectable at viewingevidence: documented80–150k km
Electric water pump and thermostat failureelectric water pump€500–€800
Overheat warning with little notice, coolant temperature swinging, sometimes an immediate limp home. The electric pump's controller fails. It's a wear item with a service life, not a fault.
Check: Age and receipts matter more than symptoms, it usually gives no warning. Treat a car past 120,000 km with no pump history as owing €600.
CoolingcommonPartly detectableevidence: documented90–150k km
Water ingress and footwell module damage1 Series platform€0–€1,200
Damp or soaked front carpets, a musty smell and fogged windows, and, when water reaches the footwell electronics, failed lights, windows or indicators. Most often the bulkhead scuttle drains block by the pollen filter and overflow into the cabin; perished door membranes and tailgate seals can add to it. Water then attacks the footwell module.
Check: Lift the front and rear carpets and press for damp. Check the boot and spare-wheel well for standing water, and confirm the scuttle drains near the pollen filter are clear.
ElectricalcommonDetectable at viewingevidence: documented60–200k km
Valve cover and PCV failureN55B30€400–€700
Oil weeping down the back of the block, whistling from the engine at idle, rough idle, high crankcase vacuum pulling oil seals. The crankcase ventilation diaphragm is integrated into the plastic valve cover, so the whole cover is the repair.
Check: Listen for a whistle at idle with the oil cap on, then remove the cap, a strong change in idle points to the PCV. Look for oil residue at the rear of the head.
EnginecommonDetectable at viewingevidence: documented100–180k km
Run-flat tyres and kerbed or cracked wheelsE9x chassis€150–€900
Harsh ride, vibration at speed, slow punctures. Stiff-sidewall run-flats transmit impacts straight into the rim, and these alloys crack rather than bend.
Check: Inspect the inner rim edge of every wheel for cracks and hairline splits, not just the face for kerbing. Budget for a set of conventional tyres; most owners switch and the ride improves markedly.
SuspensioncommonDetectable at viewingevidence: documented

Ranked by probability × repair cost, not by how loudly a failure is discussed. Inherited from the engine, gearbox, chassis and shared components, each written once. All 18 issues in full →

Pre-purchase inspection

The same issue records, reordered into the sequence you can actually check them in: cold start, static, drive, paperwork.

18 checks · saved in this browser ·

1Static checksEngine off, ideally on a lift.

2On the driveInclude low-speed manoeuvring, not just an open road.

3PaperworkOn these cars the folder is most of the value.

4OBD scanMandatory. A seller who refuses a scan has answered the question.

Mileage and servicing

What the odometer does and doesn't tell you here, plus the service items whose neglect causes the expensive failures above.

A documented DCT fluid service history matters as much as engine mileage on the automatics.

Service itemIntervalCost
Walnut-blast intake
Direct injection carbons the valves
roughly 100,000 km€300–500
DCT fluid service
Routinely skipped and expensive to ignore
roughly 60,000 km€350–600
Cooling system
Plastic parts are wear items on the turbo six
roughly 120,000 km€600–1,200

What to pay

What this engine sells for, against the median of every engine in the chassis. All figures are illustrative placeholders. See the basis chips.

Enter an asking price to get a verdict against this variant's band: cheap, fair, good buy or overpriced.

United States vs Europe

1 EUR = 1.08 USD ·
🇪🇺 Europe · EUR€13,300band €10,600–€25,700
🇺🇸 United StatesNot sold135i N55 was never a US-market car
What that meansNo US band exists to compare. Any car you find there's a private import, parts and specialist knowledge are thinner, and the price says more about import cost than about the market.

US figures are the EU band converted at a stated rate. No US market differential is modelled: we hold no sourced US asking prices, and inventing one would be worse than saying so. What the comparison does show for real is availability. Most of this range was never sold in the US.

  • ModelBMW 1 Series 135i
  • ChassisE88
  • EngineN55
  • Years2010–2013
  • MarketCentral EU
  • Windowrolling 12 months to 2026-07
€10k€15k€20k€25k◀ E88 median, all 8 engines €7,800 (off scale)Pre-faceliftPre-facelift: low €10,600, good buy €13,300, average €15,950, high €23,600€15,950€10,600€23,600€13,300Facelift (LCI)Facelift (LCI): low €11,600, good buy €14,500, average €17,350, high €25,700€17,350€11,600€25,700€14,500
Good buy at or under the marker · Median asking price · bar spans the 10th to 90th percentile · dashed line is the e88 median, all 8 engines

Good buy isn't the same as cheapest. The good-buy figure assumes the known failure items are either done with receipts or verifiably not yet due. Full breakdown by facelift phase →

Buyer notes

Our judgement, kept separate from the records it's built on.

Our read, not a record
The N55 135i is what the 135i should have been. The same 306 PS with a single twin-scroll turbo and a solenoid injector system that spares it the N54's fuel-pump and injector saga. It still carbons its valves and still wears its cooling parts, and the seven-speed DCT wants its fluid changed on time, but the frightening bills are gone. It costs more to buy than an N54 and that premium is the whole point, pay it. This is the quick E8x you can actually live with.

Everything above this line comes from the issue and specification records. This paragraph is our judgement on top of them. See how we reach it.

Full specification

Manufacturer figures for this engine and body, as recorded in the variant and engine data.

Engine codeN55B30
ConfigurationI6, single twin-scroll turbo · 2979 cc
Fuel / injectionpetrol · direct
Model years2010–2013
Facelift phaseSold either side of the 2011 facelift, 2010 pre, 2011–2013 LCI
Power / torque306 PS · 400 Nm
Transmissions6-speed manual · 7-speed DCT
Gearbox familiesGetrag six-speed manual · GS7D36-DCT
DrivetrainRWD
Economy (real-world)9–11.5 l/100 km mixed
MarketsEU