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BMW N63 Fuel Injector Failure – Symptoms & Solutions

Austin Parsons

Meet Austin

Austin graduated from the University of Colorado Denver in 2021 with a degree in technical writing and remains in the Denver area. Austin brings tons of automotive knowledge and experience to the table. Austin worked as a Technical Product Specialist at BMW for over 5 years and drives a heavily modified E30 325i with a stroker kit, all of which he built from the ground up.

The BMW N63 isn’t an engine known for reliability. At least in the early years of its production. With the introduction of later N63TU, TU2, and TU3 variants, reliability got much better than the pre-technical updated variant. One of the most significant issues with the early N63 engine was fuel injector failure. The Piezoelectric injectors that the N63 used were notoriously troublesome in other BMW engines like the N54 and early N55s as well. To add insult to injury, they are also incredibly expensive to replace.

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Fuel injector failure was so common on early N63 engines that even BMW had to acknowledge the problem in the form of a customer care package. In this guide, we’ll cover N63 fuel injector failure including the signs and symptoms of injector failure, details surrounding the problem, and repair costs associated with replacing the injectors.

If you are interested in learning about other common issues with the BMW N63 engine, take a look at our dedicated BMW N63 Engine Problems Guide and our N63 Oil Consumption Guide.

What is the Problem?

The BMW N63, along with many other early direct-injected BMWs, uses modern Piezoelectric fuel injectors to inject fuel directly into the combustion chamber. Compared to traditional solenoid injectors, Piezoelectric injectors use piezo crystals which expand and contract rapidly when exposed to an electrical current. That makes them extremely efficient and emissions-friendly. However, they are also extremely sensitive and fragile.

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The piezoelectric design of the fuel injectors is known to fail far before their projected service life. In some cases, N63 owners experienced fuel injector failure on one or more cylinders as early as 20,000-30,000 miles. BMW attributed these failures to a faulty design. The injectors tend to fail in one of two ways; the seals inside deteriorate over time, leading to the leakage of fuel. Also, the thermal compensating oil inside that cools the piezoelectric material and operates the plunger can lose its viscosity over time, causing it to not always fire properly.

BMW eventually solved the design issue with the earlier piezoelectric injectors in the later N63TU, N63TU2, and N63TU3 variants of the engine. BMW distinguished the injector designs by ‘index’ with any injectors prior to index 10 being more prone to failure than later index 11 and index 12 injectors.

Other Injector and Direct Injection Issues

While this is technically a separate issue from the piezoelectric injector failure problem, the N63 also suffered from pretty bad carbon buildup issues. Carbon buildup is a common side effect of any direct injection fueling system, as there is no fuel passing over the intake valves to clean them of carbon deposits. The only reason that I am mentioning this is because the symptoms of severe carbon buildup are often mistaken for injector failure and it is a far less expensive problem to address.

In most cases, carbon buildup on the N63 causes a rough idle, increased fuel consumption, decreased engine performance, and engine misfires. All of those symptoms are also consistent with fuel injector failure. Carbon buildup tends to get bad enough to cause these symptoms around the 80,000-100,000-mile mark. If any of those symptoms are present, it might be a good idea to look into carbon buildup first, before replacing any injectors, as it is significantly cheaper to deal with through walnut blasting. 

Symptoms of Faulty N63 Fuel Injectors

  • Rough Idle
  • Poor acceleration
  • Black exhaust tips and black residue on the bumper from unburnt fuel
  • Check engine light
  • Misfires

In most cases, a faulty fuel injector will be pretty easy to diagnose, as it will present symptoms pretty much right away. The most common symptoms include a rough idle, poor acceleration, engine stumbling, misfires, and a check engine light. Checking engine codes is the best way to determine which fuel injector is failing. Here are the most common engine codes that correspond with fuel injector failure on the N63:

  • 29E0 – Mixture control
  • 29E1 – Mixture control 2
  • 2B16 – Engine misfires, cylinder 1
  • 2B17 – Engine misfires, cylinder 2
  • 2B18 – Engine misfires, cylinder 3
  • 2B19 – Engine misfires, cylinder 4
  • 2B1A – Engine misfires, cylinder 5
  • 2B1B – Engine misfires, cylinder 6
  • 2B1C – Engine misfires, cylinder 7
  • 2B1D – Engine misfires, cylinder 8
  • 2B22 – Engine misfires, several cylinders
  • 2B23 – Engine misfires

If you notice any of these symptoms, it’s more than likely the injectors. However, these symptoms are almost identical to those of bad ignition coils and spark plugs, so we recommend replacing those parts first. Replacing all the fuel injectors at the same time will be costly given they are approx. $300 each, but may save you in labor in the long run.

It is also important to mention that when one injector fails, the other injectors, at least on the same cylinder bank, are likely following close behind it. For that reason, it is generally advised to replace all of the injectors on the affected cylinder bank at one time instead of coming back to the dealership multiple times as the other injectors begin to fail.

Can You Prevent BMW N63 Fuel Injector Failure?

While the initial fuel injector design on the N63 was the primary cause of fuel injector failure, there are some other contributing factors that also led to them failing before their projected service life. For one, using low-grade or contaminated fuels is the main cause of fuel injector failure on many of the early BMW turbo engines. 

Piezoelectric injectors are notoriously sensitive to fuel purity, so it is crucial to use only high-quality 91 and higher octane fuel when filling up. If fuel injector issues just started on your N63 and you have been using low-quality fuels, it might be enough to simply run a few tanks of high-quality fuel through them for the issue to cease. 

Outside of using high-quality fuels, some N63 owners have also discovered that some types of fuel additives can help with injector issues. Before I continue on, it is important to note that there aren’t any fuel additives that BMW has approved specifically, and no evidence from the manufacturer that they truly do help. With that said, enthusiasts in the community claim otherwise.

There are a couple of routes that you can go as far as fuel additives are concerned. The two primary types that N63 enthusiasts recommend are fuel system cleaners and octane boosters. Fuel system cleaners like BG 44K are a good additive to use every 7,500 miles or so as a way to keep the injectors clean of corrosive deposits. Octane boosters like Dynamo are another option, although not ideal, to boost the octane of lower-grade fuel, which can help with injector issues.

N63 Fuel Injector Failure Fixes and Cost

At this point, any injector repairs have to be paid for out of pocket. The good news is that the original fuel injectors have been redesigned a number of times, making them much more reliable and less prone to failure. Index 12 injectors are the newest version of the N63 injectors and are the most reliable. With that being said, they are still extremely expensive, running around $3,500 for a set of 8. A single injector costs around $450 if you don’t want to replace the whole set. With that being said, it is a good idea to replace all of the injectors on the cylinder bank where one or more have failed.

Labor is another expensive element of replacing N63 injectors. In most cases, BMW charges around 11 hours to replace all 8 fuel injectors, with a single injector being billed around 4 hours. Additionally, all modern BMW fuel injectors need to be coded to match the engine. That can range from a single injector replacement costing in the ballpark of $1,200 to $5,000 for all 8 to be replaced. 

Since it costs so much to replace them at the dealership, many DIY-inclined enthusiasts who have a bit of wrenching experience opt to replace the injectors themself. It is a long and in-depth process that requires some specialty tools, including an ENET cable for an F Chassis car, and ISTA/D to program the injectors. Here is a video that explains the process:

N63 Customer Care Package

Fixing N63 fuel injector failure isn’t as cost-effective as it used to be. At one point, BMW was involved in a class action lawsuit regarding the N63 engine, where they provided a “Customer Care Package” extended warranty that included the fuel injectors. The CCP covered vehicles under 100,000 miles or 10 years past their manufactured date which reduced the customer pay for fuel injector repair. At this point, all of the covered vehicles are past the 10-year mark, excluding E71 X6s that were produced in 2014. If you have one of those vehicles with less than 100,000 miles on the odometer, you can find details about the Customer Care Package here.

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