Car Model Guide/ BMW/ 1 Series/ E88/ 123d

123d N47S

The 123d's version of the N47: a sequential two-stage twin-turbo four making 204 PS, the most powerful four-cylinder diesel of its day. It carries the N47's rear timing-chain risk plus the extra turbo hardware, so it's quick and clever and not the one to buy without a service history.

Overview

The 123d is the N47S diesel version of the BMW 1 Series convertible (E88), sold 2008–2013 with 204 PS and manual or automatic. High risk at level 4. The N47 rear chain risk arrives with the extra sequential twin-turbo hardware, which makes this the diesel with the most to go wrong. 20 failure modes are recorded against its engine, gearbox, chassis and shared components, one of which is a walk-away item without documented proof. 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

Power204 PS

Torque400 Nm

Years2008–2013

Fueldiesel

DriveRWD

EnginesN47S

Biggest risks

Ranked by probability × repair cost. 20 recorded in total.

29High risk

Rear timing chain stretch and failure (123d)€1,500–€2,500partly checkablewalk away
"Lifetime" fluid neglect€400–€2,500partly checkable
Dual-mass flywheel and clutch wear€900–€1,600checkable

Risk level −33 · Walk-away failures −12 · Likely spend vs price −26 · all issues →

System by system9 systems reviewed · 1 with no recurring fault reported

Engine⚠ attentionRear timing chain stretch and failure (123d), €1,500–€2,500. Walk away without proof.+1 more in this system

Fuel system✓ clearNo recurring fault reported for this system on this engine.

Turbo & intakewatchVariable-vane turbo actuator sticking, €400–€1,200.

CoolingwatchCoolant expansion tank cracking, €120–€250.

Emissions⚠ attentionDPF clogging and forced regeneration, €250–€1,800.+1 more in this system

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	€5,650	€8,250	€12,400	€6,950	The specification the car launched with.
LCI Facelift (LCI)	2011–2013	€6,150	€9,000	€13,500	€7,600	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.

Rear timing chain stretch and failure (123d)N47D20 (123d twin-turbo)€1,500–€2,500

A rattle or whirr from the back of the engine, worst on cold start; at worst the chain skips or snaps and bends valves. Like every N47, the 123d mounts its timing chain at the gearbox end of the engine, where a stretched chain and worn guides can fail and take the engine with them. The higher output works the chain harder.

Check: Listen at cold start for a rear-of-engine rattle, and treat any car without documented chain work as needing it. On a 123d the repair is a large fraction of the value, so proof matters.

EnginecommonPartly detectablewalk away without proofevidence: documented90–180k 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

DPF clogging and forced regenerationDPF€250–€1,800

Warning light, limp mode, oil level rising above the maximum mark from fuel dilution. The filter needs sustained hot running to regenerate. A car used for short urban trips never completes a regeneration cycle.

Check: Read the DPF soot load and the distance since the last regeneration on a scan tool, and check the engine oil level and smell it for diesel. Ask what the car was used for. A short-trip city diesel is the wrong car regardless of mileage.

EmissionscommonPartly detectableevidence: documented120–250k 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

Variable-vane turbo actuator stickingvariable-vane turbo€400–€1,200

Sudden loss of power on a hard pull, limp mode that clears on restart, underboost or overboost codes. Soot binds the variable vanes or the actuator linkage seizes.

Check: Do a full-throttle pull in third from 1,500 rpm to the limiter. Hesitation or a drop into limp mode is this fault. Do this twice.

Turbo & intakecommonDetectable at viewingevidence: documented130–250k 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

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 20 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.

History is everything here: chain, turbos and injectors all want documentation. An undocumented 123d is the riskiest diesel in the range.

Service item	Interval	Cost
Engine oil Chain and turbo life depend on it	15,000 km or annually	€90–150
Timing chain The N47 failure that ends the engine	listen at every cold start	free
Turbo system The sequential twin-turbo setup is the extra risk over a 120d	as needed	€800–2,000

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 €8.7k

€5.7k€7.0k€13.5k

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€6,950band €5,650–€13,500

🇺🇸 United StatesNot sold123d N47S 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 123d
ChassisE88
EngineN47S
Years2008–2013
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. Any car without documentation for rear timing chain stretch and failure (123d) should be priced as if the repair is still owed. Full breakdown by facelift phase →

Buyer notes

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

Our read, not a record

The 123d is a genuinely remarkable thing: 204 PS and 400 Nm from a 2.0 diesel, quick enough to worry a 130i, on 5 l/100 km. Yet the catch is that it's the most complicated diesel here: the N47 rear chain, a sequential two-stage twin-turbo, and piezo injectors, all on one engine. Kept properly it's superb; neglected it's a stack of four-figure bills. Buy the one with the thickest folder and the quietest cold start, and price accordingly.

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	N47D20 (123d twin-turbo)
Configuration	I4, sequential twin-turbo · 1995 cc
Fuel / injection	diesel · common rail
Model years	2008–2013
Facelift phase	Sold either side of the 2011 facelift, 2008–2010 pre, 2011–2013 LCI
Power / torque	204 PS · 400 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)	5–6.5 l/100 km mixed
Markets	EU

123d N47S

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.