BMW 1 SERIES F20/F21: MOST COMMON PROBLEMS, DEFECTS, AND MAINTENANCE COSTS
The BMW 1 Series F20/F21 (2011–2019) remains one of the most popular premium compacts: rear-wheel drive, excellent driving pleasure, and lively engines. Like all cars in the premium segment, however, it comes with a list of recurring defects and maintenance costs that are good to be aware of, especially if you're considering a used purchase in 2025. In this guide, we analyze the most frequent problems with petrol and diesel engines, with causes, symptoms, and realistic costs.
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🛒 Buy now on Amazon📋 WHAT YOU'LL FIND IN THIS GUIDE
- 🔧 Engines and versions: which are the most reliable?
- ⛓️ N47 chain problem (116d/118d/120d)
- 🚗 B47 Engine Problems
- 🔥 N13 petrol engine problems (116i/118i)
- 🌀 Turbine, injectors and EGR
- 📡 Electronics, sensors and infotainment
- 💰 Maintenance costs
- 🧾 Used BMW 1 Series Checklist
- ❓ Frequently Asked Questions
🔧 BMW F20/F21 ENGINES: COMPLETE OVERVIEW
The BMW 1 Series F20/F21 is available with several engines. Here's a summary of the main ones and their actual reliability:
Gas:
- N13 1.6 turbo (116i/118i) – brilliant but delicate on the injection and chain side.
- B38 1.5 turbo (118i restyling) – more modern and reliable, reduced fuel consumption.
- N55 3.0 turbo (M135i) – very robust, but high maintenance costs.
Diesel:
- N47 1.6/2.0 (116d–120d) – great performance, but critical rear chain.
- B47 1.5/2.0 (from 2015) – more reliable, fewer timing problems.
In general, the B47 and B38 engines are the “quietest” for a used purchase.
⛓️ N47 CHAIN PROBLEM (116d/118d/120d)
This is the most well-known defect of all. The N47 engine's chain is located on the flywheel-gearbox side, making it difficult to access and expensive to replace.
Symptoms:
- metallic noise when starting (“rattling”);
- regular noise that increases with revs;
- engine light with synchronization errors.
Solutions:
- chain slack check;
- replacement of chain kit + pads + tensioner;
- possible replacement of worn gears.
Average cost: €900–1,800 depending on the workshop and accessibility.
BMW N47 – TIMING CHAIN PROBLEMS
The BMW N47 engine is known for frequent timing chain problems: noise, stretching, chain breakage, and serious engine damage. Here's everything you need to know about symptoms, causes, repair costs, and prevention.
📘 Learn more about the problem🚗 B47 ENGINE PROBLEMS (2015→)
The B47 has solved many of the N47's flaws, but it has some critical issues:
- EGR valve clogging;
- particulate filter (DPF) that regenerates too often if used only in the city;
- cold noises due to the high pressure pump.
Overall it is one of the most reliable engines in the series.
🔥 N13 PETROL ENGINE PROBLEMS (116i/118i)
This 136–170 hp engine shares architecture and flaws with the older PSA/BMW Prince engines.
Known defects:
- coils and spark plugs that burn out quickly;
- deposits on the intake valves (direct injection);
- oil leak from the sump or valve cover;
- timing chain noisier after 100,000 km.
Average maintenance cost for N13: €400–€1,200 depending on the interventions.
🌀 TURBINE, INJECTORS, EGR AND DPF
Diesel (N47/B47)
- EGR : valve and throttle body clogging.
- DPF : frequent regenerations (urban use).
- Turbine : cases of axial play beyond 150–180,000 km.
Petrol (N13/B38)
- Injectors : irregularities at idle and jerks.
- Turbine : noisy wastegate or actuator needs adjusting.
With proper maintenance, premature breakdowns are unlikely to occur.
📡 ELECTRONICS, SENSORS AND INFOTAINMENT
The 1 Series is solid, but not immune to electronic issues:
- ABS/wheel sensor that generates chain warnings;
- FRM (lights/comfort) module that can fail;
- iDrive crashing or losing settings;
- rear camera not always stable;
- control units that require software updates.
90% of electronic problems are related to a weakened service battery .
💰 MAINTENANCE COSTS (ACTUAL ESTIMATES)
| Intervention | Average cost |
|---|---|
| Full service | €180–350 |
| N47 chain kit | €900–€1,800 |
| EGR + manifold cleaning | €250–450 |
| Overhauled turbine | €650–1,200 |
| Fuel injector | €180–350 each |
| DPF replacement | €900–1,500 |
🧾 CHECKLIST BMW SERIES 1 F20/F21 USED
- Chain N47: listen to the cold start.
- DPF: check regenerations and pressure values.
- EGR: check for encrustations.
- Battery: Mandatory test (affects everything).
- Automatic transmission: check for slow gear changes or jerking.
- Engine oil: must be 100% quality synthetic.
- OBD Diagnostics: Check for errors even if there are no warning lights.
❓ FREQUENTLY ASKED QUESTIONS
Which is the most reliable BMW 1 Series?
The B38 (petrol) and B47 (diesel) versions are the most balanced and have the fewest recurring defects.
Which is better: petrol or diesel?
It depends on the use: for city trips and short journeys, a petrol engine is better; for long journeys and motorway driving, the B47 diesel is excellent.
Should N47 be avoided?
No, but it requires more attention. If the chain has already been repaired or is not making any noise, it might be a good choice.
Is maintenance expensive?
Higher than average, being a premium car. But the right engines ensure excellent durability.
SPARE PARTS AND TECHNICAL SUPPORT FOR BMW 1 SERIES
For filters, batteries, BMW-approved oil, brakes, EGR, sensors , and quality spare parts for your 1 Series, you'll find everything in our shop:
