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BMW 1 Series: N47S 2.0L twin-turbo timing chain and high-output stress (123d / 125d)

N47S 2.0L twin-turbo timing chain and high-output stress (123d / 125d) is a common engine fault on the BMW 1 Series on the 2007–2016 cars, and we rate it critical. Putting it right costs $3,000 to $6,500 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 50 documented faults on the BMW 1 Series.

Vehicle
BMW 1 Series
Only on
Bi-Turbo / twin-turbo
Engine
N47
Years
2007–2016
Fuel
diesel
System
Engine

This page covers the BMW 1 Series as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All BMW 1 Series faults50 documented faults on this model

What you are looking at

The front of a dual overhead camshaft engine with the timing cover removed, exposing the timing chain and sprockets.Example of the part — not this vehicle

The front of a twin-cam engine with the timing cover off — chain, sprockets and guides.

Logansenf · CC BY-SA 4.0 · Wikimedia Commons

What goes wrong

The 123d (E82/E81/E88) and later 125d (F20/F21) use the high-output twin-turbo N47S version of the 2.0-litre diesel - around 200-218 hp from a small four, well above the base 320d/120d. It carries the same rear-mounted N47 timing chain that is notorious for stretching, wearing its guides and, at worst, snapping and destroying the engine, but the extra output and higher fuel-rail pressure put more stress on the chain, chain tensioner and high-pressure fuel pump. Because the chain is at the back, replacement means removing the gearbox, so a proven chain history is worth a lot.

What you would notice

  • Metallic rattle from the back of the engine, worst on cold start
  • Timing/camshaft correlation fault codes
  • Chain rattle that follows engine speed
  • Hard starting or rail-pressure faults (high-pressure pump)

How to check it

Where to look. Timing chain at the rear (gearbox end) of the 2.0-litre engine

  1. On a genuinely cold first start, listen at the rear of the engine (bulkhead/gearbox end) for a chain rattle - any sustained rattle is a walk-away unless the chain is proven done.

  2. Ask for invoices showing the timing chain kit and, ideally, whether the updated (post-2011 TU) parts are fitted.

  3. Scan for timing and rail-pressure codes.

Parts involved: Timing chain, Turbocharger.

What it costs to put right

$3,000 to $6,500 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

  • “Has the timing chain been replaced, and with updated parts?”
  • “Does it rattle from the back of the engine on cold start?”

Now check the BMW 1 Series you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.

Not sure what you would be paying for? See what a full KickTyres check includes.

Where this comes from

The failure described above is documented in the sources below. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them.

  • PistonHeads '123D reliability? Timing chain?' thread
  • BabyBMW.net '123D reliability issues? Timing chains etc?' thread
  • TecAlliance TB0092 'BMW N47 Timing Chain Issues' technical bulletin

BMW 1 Series buyer questions

Is n47s 2.0l twin-turbo timing chain and high-output stress (123d / 125d) serious on a BMW 1 Series?

We rate it critical and common on the BMW 1 Series. The 123d (E82/E81/E88) and later 125d (F20/F21) use the high-output twin-turbo N47S version of the 2.0-litre diesel - around 200-218 hp from a small four, well above the base 320d/120d. It carries the same rear-mounted N47 timing chain that is notorious for stretching, wearing its guides and, at worst, snapping and destroying the engine, but the extra output and higher fuel-rail pressure put more stress on the chain, chain tensioner and high-pressure fuel pump. Because the chain is at the back, replacement means removing the gearbox, so a proven chain history is worth a lot.

How much does it cost to fix on a BMW 1 Series?

$3,000 to $6,500 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which BMW 1 Series years are affected?

Our research records this fault on the 2007–2016 BMW 1 Series. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.

How do I check for it before I buy?

On a genuinely cold first start, listen at the rear of the engine (bulkhead/gearbox end) for a chain rattle - any sustained rattle is a walk-away unless the chain is proven done. Ask for invoices showing the timing chain kit and, ideally, whether the updated (post-2011 TU) parts are fitted. Scan for timing and rail-pressure codes. Look here: Timing chain at the rear (gearbox end) of the 2.0-litre engine