Introduction
The BMW 320d (E90) with the N47 four-cylinder diesel is one of the best-selling 3 Series models on the German market. Fuel economy is low and the engine runs smoothly. The main design risk is the timing chain, located on the flywheel side of the engine. If the chain has already been replaced or its replacement is scheduled, the car is an economical, long-distance-capable daily diesel.
Body Styles
The model was built in three body styles, each with its own set of engines.
| Body | Type | Production Years | Engines |
|---|---|---|---|
| E90 | Sedan | 2005–2011 | N43, N46, N47, N52, N53, N54, N55, M57 |
| E91 | Touring | 2005–2012 | N43, N46, N47, N52, N53, N54, N55, M57 |
| E92 | Coupe | 2006–2013 | N43, N46, N47, N52, N53, N54, N55, M57, S65 |
The N47 Engine
The N47 is a four-cylinder diesel. The N47D20A version makes 177 hp and 258 lb-ft of torque; the early N47D20 makes 163 hp.
| Version | Power | Torque |
|---|---|---|
| N47D20A | 177 hp | 258 lb-ft |
| N47D20 (early) | 163 hp | — |
The M47 came before this family. From 2014 on, the successor is the B47, a 2.0-liter modular diesel. In the B47 the timing chain was redesigned and moved forward, to the front of the engine. Typical B47 topics: the EGR cooler (subject to a recall campaign), diesel particulate filter (DPF) loading, and the AdBlue/SCR system.
Transmission
The diesel pairs with a ZF 6HP19 automatic transmission. The fluid gets changed every 50,000–62,000 miles.
Maintenance Schedule
| Service | Interval |
|---|---|
| Oil change (5W-30 LL-04) | every 9,300 miles / 1 year |
| Fuel filter | every 37,000 miles |
| ZF 6HP19 automatic transmission fluid | every 50,000–62,000 miles |
| Brake rotors and pads | 37,000–62,000 miles |
| EGR cleaning | as needed |
| Timing chain + tensioner (preventive) | recommended from 93,000 miles |
| DPF cleaning | 93,000–124,000 miles |
Common Problems
The N47 Timing Chain
The most common and the most expensive problem. The chain sits at the rear of the engine, on the flywheel side. Failures are documented in the 75,000–124,000-mile range. The symptom is a rattle (Rasseln) on cold start. Diagnostic codes: 2A82, 2A87, P0016.
The repair is labor-intensive: to reach the chain, the transmission and flywheel have to come out. Budget-wise, the job is comparable to a serious engine rebuild.
EGR Valve and Cooler
The system is prone to coking (Verkokung), and the cooler sometimes develops leaks. The valve logs under code 490A, the cooler under 490B.
Swirl Flaps (Drallklappen)
The flaps in the intake manifold wear out. A common fix is disabling them (Stilllegung). Code: 493B.
N47 Oil Separator (KGE)
The membrane in the crankcase oil separator cracks, which leads to oil consumption and blue smoke out of the exhaust. Replacing the unit is one of the inexpensive jobs.
DPF Loading / Short Trips
The diesel particulate filter clogs with city use and short trips. Code: 4F8C.
Fault Codes
| Code | System |
|---|---|
| 2A82 | N47 timing chain |
| 2A87 | N47 timing chain |
| P0016 | N47 timing chain |
| 490A | EGR valve |
| 490B | EGR cooler |
| 493B | Swirl flaps |
| 4F8C | DPF loading |
Diagnostics
A cold-start rattle is the first sign of a worn chain. Before replacing injectors, always measure the return flow (Rücklaufmenge): often only one injector is bad, not the whole set.
Related Repairs
Some components are replaced in parallel, at similar mileage.
- Replacing a single injector is moderately priced; a full set on the four-cylinder is expensive, and on a six-cylinder even more so.
- Water pump: the electric unit on the N52/N54/N55 is moderate, done together with the thermostat; the mechanical pump on the diesel is moderate; on the B47/B48/B58, moderate as well. The aftermath of overheating is very expensive—comparable to an engine rebuild.
- Intake manifold: walnut blasting (Walnussstrahlen) is moderate; full replacement is expensive; replacement with swirl flap repair is expensive. Cleaning or replacement makes sense for diesels from 75,000 miles and for the direct-injection N53/N54 engines from 50,000 miles.
Shop Practice
- EGR cleaning is done as needed, not on a schedule.
- The EGR cooler is prone to leaking—and the leak isn’t always found right away.
- Swirl flap deletion is a mass practice, not a one-off measure.
- The timing chain is the key item when inspecting a used 320d (E90).
- Service history, the condition of the KGE oil separator, and the swirl flaps are must-check items in a pre-purchase inspection.
Contradictions in the Data
- The preventive recommendation to replace the timing chain from 93,000 miles conflicts with documented failures starting at 75,000 miles. The thresholds contradict each other.
- The EGR weak point is listed under code 490A in one place and additionally under 490B (EGR cooler). The mapping of code to a specific component is ambiguous.
- The timing chain codes appear sometimes as a group (2A82/2A87/P0016), sometimes on their own (2A82). The presentation is inconsistent.
Buying Verdict
Buy only with the timing chain already replaced, or with its repair scheduled immediately. Once the chain is sorted, the 320d (E90) is an economical, long-distance-capable daily diesel. Without documented proof of the chain replacement, the inspection calls for caution and a scheduled shop visit.
FAQ
How much does a timing chain replacement cost on a 320d (E90)?
The job is expensive: the transmission and flywheel have to come out for access, so the cost is comparable to a major engine rebuild.
How much horsepower does the 320d (E90) have?
The N47D20A makes 177 hp and 258 lb-ft; the early N47D20 makes 163 hp.
Is it a good car to buy?
Yes, if the timing chain has already been replaced. Without proof, inspect with caution and plan the repair.
The Bottom Line
The 320d (E90) with the N47 is economical and long-distance-capable, but the whole economy hinges on one part: the timing chain on the flywheel side. As a buyer, get the chain replacement documented, and during the inspection check the condition of the KGE oil separator and the swirl flaps.