Car Model Guide/ BMW/ 1 Series/ E88/ 118i

118i N43

Lean-burn direct-injection four. Economical when healthy and expensive when not. The injectors and NOx sensors are the whole story.

Overview

The 118i is the N43 petrol version of the BMW 1 Series convertible (E88), sold 2008–2011 with 143 PS and manual or automatic. Demands diligence at level 3. Piezo injectors and NOx sensors are the recurring cost, on a car whose value doesn't cover many of them. 19 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) · photo 2008-2010 BMW 120i (E88) convertible (2010-05-19) 01 by OSX · Public domain · Wikimedia Commons

Power143 PS

Torque190 Nm

Years2008–2011

Fuelpetrol

DriveRWD

EnginesN43

Biggest risks

Ranked by probability × repair cost. 19 recorded in total.

52Demands diligence

"Lifetime" fluid neglect€400–€2,500partly checkable
Dual-mass flywheel and clutch wear€900–€1,600checkable
Carbon buildup on intake valves€400–€700not checkable

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

System by system9 systems reviewed · 0 with no recurring fault reported

EnginewatchTiming chain tensioner rattle, €300–€1,400.

Fuel systemwatchPiezo injector failure (lean-burn petrol), €350–€500.

Intake & airwatchCarbon buildup on intake valves, €400–€700.

CoolingwatchCoolant expansion tank cracking, €120–€250.

EmissionswatchNOx sensor failure, €300–€600.

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.

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.

Phase	Years	Low	Average	High	Good buy	What differs
pre Pre-facelift	2008–2010	€3,400	€4,950	€7,100	€4,200	The specification the car launched with.
LCI Facelift (LCI)	2011	€3,750	€5,400	€7,700	€4,600	N55 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.

"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

Timing chain tensioner rattleN43B20€300–€1,400

Rattle for one to three seconds on cold start, worst after the car has stood overnight. The hydraulic tensioner bleeds down. Caught early it's a tensioner; ignored it becomes chain and guides.

Check: The car must be stone cold. Stand outside it at start-up and listen for a rattle from the front of the engine.

EnginecommonDetectable at viewingevidence: documented100–180k 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

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

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 19 issues in full →

Mileage and servicing

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

Scan for injector and NOx faults rather than trusting the mileage. Injector index history is the number that matters.

Service item	Interval	Cost
Engine oil Injection-system longevity follows oil quality	12,000–15,000 km	€90–150
Injector/NOx scan The only honest read on the fuel system	on purchase	free

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.

median €5.2k

€3.4k€4.2k€7.7k

Cheapfind the reasonGood buyif it checks outFairnormal moneyOverpricedneeds justifying

Asking price (€)Mileage (km)

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 · 2026-07

🇪🇺 Europe · EUR€4,200band €3,400–€7,700

🇺🇸 United StatesNot sold118i N43 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 118i
ChassisE88
EngineN43
Years2008–2011
MarketCentral EU
Windowrolling 12 months to 2026-07

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 N43 118i is the mainstream facelift petrol and a good car with one running-cost asterisk. The piezo injectors and NOx sensors that make it economical are also what make it expensive when they fail. Then budget for them, buy one with evidence they've been addressed, and it's a fine everyday choice. Ignore the fuel system and it becomes a limp-mode car with a €2,000 quote.

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 code	N43B20
Configuration	I4, naturally aspirated, lean-burn · 1995 cc
Fuel / injection	petrol · direct
Model years	2008–2011
Facelift phase	Sold either side of the 2011 facelift, 2008–2010 pre, 2011 LCI
Power / torque	143 PS · 190 Nm
Transmissions	6-speed manual · 6-speed automatic (ZF)
Gearbox families	Getrag six-speed manual · ZF 6HP19 / 6HP21 six-speed automatic
Drivetrain	RWD
Economy (real-world)	6.5–8 l/100 km mixed
Markets	EU

118i N43

Overview

Pre-facelift or facelift, this engine spans both

Known issues, ranked by expected cost

Pre-purchase inspection

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.