Fuel injector failure
Attaches to N54 at engine level · Fuel · carried by 6 variants across 5 chassis
Overview
Fuel injector failure is a common fault recorded against N54 at engine level, typically from 80–180k km. It shows up as rough idle, cold-start stumble, misfire counts on one or two cylinders, occasional fuel smell. Where it's documented, the repair runs €1,800–€3,000 (full set of six at an independent, costs dated 2026-07), and it can be partly checked before you buy. 6 variants across 5 chassis in this database inherit it.
What happens
Symptom. Rough idle, cold-start stumble, misfire counts on one or two cylinders, occasional fuel smell.
Cause. Piezo injectors leak or lose spray pattern. BMW revised the design repeatedly. The index number on the injector tells you which generation is fitted.
Sources. BMW injector index revision programme
How to check it
OBD scan
Scan for per-cylinder misfire counts on a warm engine. It is the only honest check. Ask which injector index is fitted. Assume a car with no injector history will need some.
Mandatory. A seller who refuses a scan has answered the question.
Every variant that carries this
| Variant | Chassis | Body | Years | Risk | Good buy | Cost as % of good buy |
|---|---|---|---|---|---|---|
| 335i N54 | E90 | sedan | 2006–2010 | R4 | €7,350 | 33% |
| 335i N54 | E92 | coupe | 2006–2010 | R4 | €8,450 | 28% |
| 335i N54 | E93 | convertible | 2007–2010 | R4 | €8,250 | 29% |
| 135i N54 | E82 | coupe | 2007–2010 | R4 | €9,800 | 24% |
| 135i N54 | E88 | convertible | 2008–2010 | R4 | €10,350 | 23% |
| 1M N54 | E82 | coupe | 2011–2012 | R3 | €50,700 | 5% |
The last column is the point. The same repair is an inconvenience on one variant and a reason to scrap the car on another. A failure costing a quarter of the vehicle's value changes the purchase decision regardless of how rare it is.