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CriticalCommonEngine

BMW 1 Series: N20 2.0T timing chain guide failure (125i)

N20 2.0T timing chain guide failure (125i) is a common engine fault on the BMW 1 Series on the 2011–2015 cars, and we rate it critical. Putting it right costs ≈A$2,300 to ≈A$5,060 at independent workshop rates, shown as an approximate guide in Australian dollars. 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 54 documented faults on the BMW 1 Series.

Vehicle
BMW 1 Series
Engine
N20
Years
2011–2015
Fuel
petrol
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 faults54 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

Early production N20 2.0T petrol engines use plastic timing chain guides that crack and disintegrate prematurely, introducing slack into the chain. A jumping chain causes severe valve and piston damage. BMW acknowledged the defect via TSB SI B11 09 17 and issued a limited warranty extension to 7 years/70,000 miles under SI B11 03 17 (October 2017), covering N20 and N26 engines produced through approximately February 2015. Engines produced after February 2015 received updated guide materials from the factory.

What you would notice

  • Metallic rattle from engine on cold start that may diminish when warm
  • Rough idle and misfires at light throttle
  • Check engine light with cam-crank correlation or misfire fault codes
  • Noticeable power loss across the RPM range

How to check it

Where to look. Front of engine, timing chain cover area

  1. Listen for cold-start chain rattle from the front of the engine.

  2. Identify the build date on the VIN plate – units built before February 2015 are highest risk.

  3. Scan ECU for P0016, P0017 or related cam/crank fault codes.

  4. Confirm whether the BMW warranty extension (SI B11 03 17) was applied at a BMW centre.

  5. Review any service records mentioning timing or chain work.

Parts involved: Timing chain.

What it costs to put right

≈A$2,300 to ≈A$5,060 at independent workshop rates, shown as an approximate guide in Australian dollars. That is for this job on its own, not for the car.

An estimate, converted to Australian dollars, 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, chain guides, or tensioner ever been replaced?”
  • “Was the BMW N20 timing chain warranty extension (TSB SI B11 03 17) carried out at a BMW dealer?”
  • “What is the vehicle's production date, and has it had any rattle or misfire history?”

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 still has money owing on it, has been written off or reported stolen, what kms it showed in past sale ads, whether it has had accident repair claims and what it is worth today. That comes from the official records for that plate. Enter the plate and its state for the A$17.90 Vehicle Check, or the full history from A$24.99.

Where this comes from

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.

BMW 1 Series buyer questions

Is n20 2.0t timing chain guide failure (125i) serious on a BMW 1 Series?

We rate it critical and common on the BMW 1 Series. Early production N20 2.0T petrol engines use plastic timing chain guides that crack and disintegrate prematurely, introducing slack into the chain. A jumping chain causes severe valve and piston damage. BMW acknowledged the defect via TSB SI B11 09 17 and issued a limited warranty extension to 7 years/70,000 miles under SI B11 03 17 (October 2017), covering N20 and N26 engines produced through approximately February 2015. Engines produced after February 2015 received updated guide materials from the factory.

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

≈A$2,300 to ≈A$5,060 at independent workshop rates, shown as an approximate guide in Australian dollars. 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 2011–2015 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?

Listen for cold-start chain rattle from the front of the engine. Identify the build date on the VIN plate – units built before February 2015 are highest risk. Scan ECU for P0016, P0017 or related cam/crank fault codes. Confirm whether the BMW warranty extension (SI B11 03 17) was applied at a BMW centre. Review any service records mentioning timing or chain work. Look here: Front of engine, timing chain cover area