The original BMW 335i is a bit of a marvel. At the time of its release, everyone thought BMW had gone mad. Why sacrifice the character of a naturally-aspirated engine when the German marque could’ve just built a modern version of its M30 big-six? Well, it wasn’t long until drivers noticed smooth, almost lag-free power delivery and tuners realized they could add the better part of 100 horsepower with a few bolt-ons and a tune. How’s that for a bit of humble pie? However, as these cars depreciated, it became apparent that they were quite expensive to keep going, and over the past few years, the costs have grown much higher.
Really, it’s not just the 335i I’m talking about – it’s anything with the N54 twin-turbocharged inline-six engine. Certain years of 135i, 135is, Z4 sDrive35i, Z4 sDrive35is, 335is, 535i, X6 xDrive35i – all that stuff. The N54 is a neat engine, but almost everything bolted to it is terrible. The turbochargers develop wastegate rattles that require serious hours to repair, the plastic valve cover cracks, the charge pipes leak, and the high-pressure fuel pump can go bang. However, most of these pale in comparison to the issue of fuel injectors.
The N54 uses piezoelectric direct fuel injectors, and because it’s a fairly early application of this tech on a gasoline engine, they tend to go a bit wrong. BMW had to revise injector design 11 times during the engine’s production, eventually landing on the latest Index 12 injectors. However, Index 12 injectors can still fail, and you’re not ready to hear what each replacement injector costs.
Take a deep breath. From reputable online retailer FCP Euro, Index 12 injectors for the N54 inline-six cost $549.99 each. Yes, each. What’s more, it’s not recommended to mix Index 12 injectors with Index 1-10 injectors as a calibration change occurred for Index 11, which means that it’s recommended to replace injectors bank-by-bank. Considering an N54 has two banks of three cylinders, this means a minimum outlay of $1,649.97. If you want the peace of mind of replacing all six in one go, that’s $3,299.94 worth of fuel injectors. That’s enough to mechanically total a high-mileage E90 335xi.
Index 12 injectors weren’t always this expensive, so what the hell happened? In short, there was a parts structure change. The updated fuel injectors for the N54 engine carried a part number of 13538648937 and were made unavailable outside of recall or warranty work in 2018. However, they were basically identical to the then-recently updated direct injectors found on the S63 V8, part number 13538616097. Both part numbers have since been combined under part number 13538616079, still identical to the injectors on the S63, albeit much more expensive than before.
So are there any aftermarket alternatives to these pricey VDO-manufactured injectors? Yes and no. There are companies out there that promise to rebuild these fuel injectors. However, rebuild quality varies wildly, so it’s a roll of the dice on whether you’ll need to just buy brand new injectors anyway. I’d also advise against ordering cheaper injectors from eBay as many are counterfeit with improper calibration values printed on the parts. As replacing N54 injectors requires registering the new injectors in the engine control module, punching in correct injector calibration values is critical to avoid misfires.
As it sits, there is no cheap way to properly replace N54 fuel injectors according to servicing guidelines. It’s a painful reminder that once-bleeding-edge technology will always be expensive to keep going as few first shots are ever perfect. If you’re in the market for an N54-powered BMW, it’s a good idea to ask for service records and see if the injectors have ever been replaced. If all six are now Index 12 injectors, you’re likely in the clear. If not, be sure to keep a few grand lying around for when the inevitable happens. Really, that’s good German car advice in general.
Lead photo credit: BMW
I wonder if a certain German lighting enthusiast site posted a lazy article that influenced the creation of this.
This is exactly why I went from scoping $15k 335is up to 2014+ $20k 335is. I read into the headache of the twin turbo and HPFS and noped right up to a slightly bigger monthly payment. I wanted something off lease or warranty, around 50k miles, and something I was going to work on myself, so BMW inline 6. As soon as I read into the N54 stuff, I realized why they were considerably cheaper than the updated N55 and full generation jump up to FX.
I did the retirement trip with my Montero and rolled 300k miles in Moab, and got to online shopping and saving. Before the pandemic I was dead set on flying to LA or NYC to get a good one with a stick in an interesting color, as the Denver market was scarce and ones in that price range disappeared same day every time, and one in an interesting color with a manual and optioned out? Once every 3-5 months from my searching. I broadened a bit and reminded myself that since it was a long term daily, I could comprimise a bit since I was getting married, and get the F43 GT with the long wheelbase and almost wagon storage capabilites, tons of legroom in the back, rear bias AWD + an extra 1.5″ of clearance for the CO winters. The ZF-8 is really fun, plenty snappy, and when I pick up an ugly 235i as a track toy I will make sure that one is a stick.
When I had an injector fail on my 335xi, I just bought a reman one for like $75 and flashed it myself. This was after a dealer quoted me 6 injectors and an ECU plus labor to fix a code that clearly stated which injector was failing. The injector repair is only expensive if you buy the BS that you need to buy all 6 and all of the newest spec when one goes bad.
Dude you’re awesome. This is exactly the approach I take with my Bimmer.
Unfortunately there is no such thing as a remanufactured piezo injector for N54 (and N53). All they can do is clean and test. If the injector leaks or is out of spec, it’s game over and a new injector is required. ATM in UK a new one from BMW is £450. That is a complete rip-off. New alternatives are unavailable.
It’s pretty clear that there are many, many cheap aftermarket suppliers for these injectors. Some are junk of course, but I’m sure most will work just fine. Do some research on a reputable rebuilder to make you feel better.
As far as calibration code, I know that in an HD diesel engine you’ll generally be ok with the wrong code, but obviously not optimized. Far from presenting a misfire though.
In Fleet vehicles, cal codes are often ignored, as the difference cannot be felt, although I do always input the updated code. Also in Fleet vehicles, replacing more than the failed injector is never an option, and presents absolutely no reliability or performance issues.
Do these bmw injectors run so far out of their operating envelope so as to cause a misfire due to the wrong cal code? Probably sometimes, but most of the time you’re probably fine, except for the knowledge that one cylinder may be contributing a few percent more or less than the others.
In a newer car under warranty, these issues would concern me, but in an old beater bmw, a single different injector would be just fine.
So my takeaway is that this issue can be fixed for a few hundred bucks and an indeterminate amount of elbow grease.
The only other question is whether the initial injector failure caused catastrophic engine damage…
Ok….if you own a 335i, then you need to own a proper scanner. Whether you use a Foxwell or a smartphone scanner, the BMW coded scanner will register new parts, so that is not an issue.
If you own a N54 and you haven’t upgraded your charge pipe (to a metal one), your injectors to Index 12, 40k Walnut interval blast interval with coil and plugs, PVC valve upgrade, monitored your oil gasket housing, checked your motor mounts and power steering bolts each oil change…etc..by now…you can’t afford it. These vehicles require precise maintenance and proactive maintenance to keep them it the tip top.
This may sound like a lot, but the rewards of a base 300hp at the wheel and modest tune to 360hp in a German engineered beast is not much. Yes there are a lot of weak points outside the powerhouse, but if you are proactive, you can truly enjoy this driving experience worry free. I believe the record stock build set up with tune is 500hp. Upgrade the twin or go for a big single turbo and you are easily in the 500-600hp territory. Close the deck, and have at it and you are in the 600-800hp league.
If you haven’t replaced your injectors to Index 12 by now, this is on you. This is a platform closing in on 20 years with the Index 12 being one of the primary maintenance upgrades. Last year this would have costed $1200. A couple prior was only $800. You snooze, you lose.
BTW, if you go with FCP, you get 60% off of OEM BMW pricing (BMW OEM parts) with a lifetime warranty.
or you can roll the dice and for $150 Canadian bucks you can get the finest:
https://www.aliexpress.com/item/32896814410.html
There was also a $75 one, but a 1 star rating, don’t want to push your luck!
Added to cart.
How are the old injectors breaking, and how long can the 4th owner limp the car around while it is doing that?
BMW maintenance is a killer. I had a E39 528i M-Sport which i really loved, but the maintenance just killed it for me and made me end up resenting the car. They just aren’t built to last. Why BMW uses so many plastic parts that grow brittle over time is beyond me.
Because all they are interested in is selling cars that last for their pitiful warranty period. After that they have no concern.
BMW: Broke Man Walking
Break My Wallet.
This particular part also seems to have been hit hard by the global supply chain issues and inflation.
I got my set of 6 from FCP in November 2020 for $1308. A year later, they were over $2400, and now they’re over $3300. That lifetime warranty will sure pay off if I ever have to replace them again!
They can be coded at home with a sub-$200 scan tool.
You don’t understand the soul of fine machinery. You lease it for three years and then laugh at the poor schmuck who buys the time bomb with the shorter fuse.
If you have to pay labor that’s probably almost $5000, which is buy a whole car money. GDI can be done better, partly by waiting for more mature technology and partly by having the Japanese engineer it. The Mazda Skyactiv engines are generally reliable and don’t even have a lot if carbon issues. Toyota moved late and their new GDI engine has secondary port fuel injection to keep the intake valves clean
“But, but BMW makes the best cars ever! Except for the 900+ engineering defects per model and the 1000+ undisclosed TSBs! But you’ll never have problems getting parts, until they abruptly quit making it because they don’t want to honor the warranty from a court settlement.”
Oh, and speaking of piezoelectric DI systems. GM also uses one in 362 different variants across all brands between 2013 and 2020. SIDI is Bosch piezoelectric because Siemens sucks ass. (No, seriously. They’re like 2000psi – the GM Bosch part is 2200-2700psi normal operating.)
Said injectors cost $110 each. At the dealer. (But maaaaaan, fuck sealing them.)
No joke. This is not new technology and many manufacturers uses them. If the owner hasn’t done their homework and been practive, the the price gouging is really on them.
Wait till he goes for a Walnut blast which is common for direct injection systems.
If these aren’t M cars, I can see how a non-enthusiast could end up owning one without too much pre-purchase research.
These are lower-end luxury models. I would suspect that any other vehicle of similar type / mileage / age could be sitting on a maintenance issue of similar value.
I chose to not buy an M and went with the N54. A low mileage with all the service documentation and a pre-purchasr inspection left me with a healthy specimen.
I do put about $2k into it each year on proactive maintenance, but it’s paid for and fun to drive. In 5 years I only came home once in limp mode for a LPFP sensor failure (easy $70 replacement) and a tow for for the water pump (yeah this is one of their weak points as they are electronic and can fail with no notice..was $1600 with warrantied replacement including labor).
But why a N54 over a M? A simple modest tune made it more powerful. The only real upgrade for the M is a supercharger which is pretty dang expensive. And premature rod bearing failure is not a cheap repair/maintenance bill.
No different than owning a diesel truck cost wise, maybe actually cheaper as the labor on these injectors is cheaper. I service a dozen or so of these and have only seen one injector failure this far, a few are well over 200k miles.
Whenever articles like this show up, for my own amusement I always compare the parts cost to a Viper with its limited production, bespoke drivetrain.
An OEM fuel injector for a Gen V is $55.
Lest you think it’s a direct injection thing, a C8 Corvette injector is $48.
You have choices, people. The American manufacturers don’t do everything right, but damned if it isn’t a lot easier to keep them on the road.
You really have to wonder about the engineering decisions that got us to GDI. Yes, it offers slightly better performance/economy but at such a complexity/reliability cost. Between HPFPs going bad and gummed up intake valves to crazy expensive injectors, you have to think that Port Fuel Injection was the peak engine tech.
“Yes, it offers slightly better performance/economy but at such a complexity/reliability cost.”
Sightly better?
The 167HP/168ft-lb PFI 2.5L MZR equipped Mazda 3 was rated at 22/29/25 while the 187HP/186ft-lb DI 2.5L SkyactivG Mazda3 is rated at 27/36/30. That’s a gain of 20% fuel economy with a bit more power to boot.
IIRC, there was more to the SkyActiv engine than just GDI – and the MZR in my 2006 MazdaSpeed 6 was GDI.
Toyota D4S. It’s been around since at least 2006, longer than the 335.
Best of both worlds and reliable.
Isn’t a big share of the problem the garbage quality fuel on offer in the US?
Nope. Same issues in UK. Let’s not blame the fuel: the car should run on what’s available.
Years back I used to buy remanufactured Chevy 350 V8’s from Pep Boys for $550. The whole engine. For the same price as one single BMW fuel injector.
Years back? How many years ago could you by an LS motor for $500? I’m calling BS on this one.
Chevy 350 is not an LS. He’s talking about an older small block Chevy, and yes, they were that cheap at one point.
It was probably some time in the 1960s or 1970s.
If the year was 1970. Then the US$550 back then would be about US$4200 today. And you can get replacement Chevy 350 V8s for that little and far less:
https://www.jegs.com/p/JEGS/JEGS-Small-Block-Chevy-350ci-57L-Crate-Engine/5244244/10002/-1
And actually, you can get an engine and transmission kit for that same inflation-adjusted amount these days:
https://www.jegs.com/i/JEGS/059/7353K8/10002/-1
So technically, it’s CHEAPER to buy a replacement for an old Chevy 350 these days than it was back then… assuming my inflation adjustments are more or less correct.
Hence the reason I opted for the 128i. Not as much power but, so far, not nearly as many issues. *knocks on wood*
I could have written this article alot shorter. Why are they ticking time bombs? They are BMWs. I suggest an article written by an automotive engineer and an automotive bean counter. What is the ideal point between a well built car that lasts through the warranty and provides the original owner decent resell value, while falling apart quickly enough that providing parts long term and long life doesn’t result in loss of sales of newer vehicles. There is a term in business planned obsolescence. Design and build a good product that needs replacement regularly. The cell phone manufacturers have perfected this process.
Maybe they should take a page from the phone playbook and start making it so OTA updates of the vehicle software somehow make it function worse and worse until you buy a new one out of sheer frustration because something that worked fine two years ago now can’t handle the exact same basic tasks it used to do with ease.
“Maybe they should take a page from the phone playbook and start making it so OTA updates of the vehicle software somehow make it function worse and worse until you buy a new one out of sheer frustration because something that worked fine two years ago now can’t handle the exact same basic tasks it used to do with ease.”
if you’re on Android, LineageOS is your friend.
https://www.makeuseof.com/lineageos-best-android-custom-rom/
The Jag AJ133 and AJ126 engines have similar issues with the injectors and similar quoted costs to fix. In the Jags it is usually excess fuel gumming up the injectors, not idea if it is the same for BMW? The forums all say to use a high grade fuel a regular use of injector cleaner to mitigate (but doesn’t eliminate) the chances of a failure. I also suspect excessive use of the burble tune in dynamic mode (on the F Type especially) maybe a contributing factor?
Pish tosh. Jaguar V-6 fuel injectors (2016 F-Type supercharged six-cylinder) made by Bosch are 74 bucks on Rock Auto. Jaguars have some curious faults but parts, at least aftermarket parts, are pretty reasonable if not cheap.
Wouldn’t be surprised there are even cheaper Ford part numbers for a lot of the engine parts as many are based on Ford engines or used in Ford models, notably the early-aughts Thunderbird.
I had to sell my ’09 135i (manual) when we moved countries back in 2015, I wish I’d shipped it, but anyway… but it kinda sounds like I dodged a bullet as all these issues with those engines keep cropping up. I’m stupid enough to buy another though… so theres that.
Had they still been making the 135i when I retried, I would have bought one. The HPFP doesn’t wait to go south on the N54s either. Although I likely would have wound up with an N55, I agree I dodged a bullet.
I still may get a 128i one day, though.
I really should sell my 08 335xi, but it’s been a fun ride for a long time, so it’s hard to let it go. Did the HPFP dance twice early on, but after that settled down.
This type of proprietary, John Deere-esque parts programming, features-as-you-go subscription bullshit is rampant, not just in cars, but other products too. Things you wouldn’t even suspect. My wife was looking for a wireless lawn sprinkler controller. Reasonable price and a lot of nice features. It lets you activate specific zones, it is tied to WiFi so it can shut them off if rain is reported in your area, all kinds of neat stuff. Oh, but wait. All of those features are offered with a free one month subscription. Yep, pay as you go after that. I’d rather pay more upfront instead of being soaked (no pun intended) indefinitely. I’ll keep using my analog controller. These other guys can go out of business as far as I’m concerned.
This vehicle is too old for any subscription based service, so I fail to see how this applies.
I think proprietary to the point that aftermarket alternatives are seen as potential counterfeits – which only becomes a problem when you have to pair the replacements with the OEM ECU, which I assume requires a dealer service department-level computer (which again brings us to the OEM version is prohibitively expensive and anything not direct from the OEM is suspect).
It’s less about it being proprietary as much as it is that every high pressure direct injector flows a little differently, so they’re testing and coded during production. All you’re doing is telling the ECM the flow rate so it knows what the expected pulse width is. It’s not just BMW, it’s all of them, from Powerstrokes, to ecoboosts
Everything I’ve replaced in my 335i has not been OEM, so I don’t know what you’re on about. If you buy OEM parts you might as well set your money on fire. Fuel injectors not withstanding, I don’t know about that.
There are definitely open-source alternatives that could duplicate that function. It is kind of terrible that your only two options are weekly adafruit deliveries for your arduino-based sprinkler controller project or sell your sprinkler data (I’m sure it’s valuable to someone) and pay for the privilege on a monthly basis.
I bought a thermometer that had an app for remote monitoring. In order to use the app I need to give the app access to my phone’s location. No functionality without that permission. I just decided to walk upstairs and read the digital display. I suspect that a lot of people would just allow all permissions without considering them. There would be barely more consideration for permissions plus monthly fees.
That’s because Google bundled Bluetooth with location access permission a few years back. No location permission, no Bluetooth access for you!
The injectors require registration and calibration?
I seriously doubt that I will ever purchase another new vehicle. I just couldn’t deal with the inflated prices, electronic nannies, and ridiculous engineering.
It’s BMW, you have to register the battery with the ECU
But when you register the battery, you are telling the ECU how to charge the battery in general. It will gradually lower the charging based on the battery expected life to increase its life in general. You can pay $160 for the register with a mechanic or own a $160 scanner that will also register new parts. Or for $100 you can buy a smart phone app scanner that will register new parts.
And anyone throwing a battery in theirs most likely has the scanner if they do any work on theirs to begin with.
Everyone should have a decent scanner honestly.
There’s no scanner involved with registering the battery. As my university physics professor used to say, that’s a bunch of hooey.
A proper BMW code scanner also has the ability to insert the part code for the ECU for calibration.
It’s not worth trying to split hairs on this one.
Not entirely true. I bought a cable for $40 and downloaded free software. I bought the new battery for $220 at Batteries Plus ($500 at the stealership). But then again, I’m awesome.
Still probably better then when another certain German brand decided to change from a timing belt to a timing chain, and because it was a “lifetime” chain, they put it on the back of the engine as it did not require service like the timing belt did.
So, of course, it was not actually “lifetime”.
It was lifetime… of the warranty!
Or when that same German brand (I think) decided to change from oil rings that have worked forever to a “new” design. A new design that guaranteed your engine would burn oil and lose power. The solution, rebuild the engine with new pistons, new rings (old new design) and there you go.
From what I read, when company A discovered they had this problem, they wondered what to do …
Enter company V. They used the same engine, for the most part, so company A started using company V’s pistons and rings. Handy fix!
I have the pre-chain version of that and they still have their problems, particularly with the tiny cam chains that don’t stay tensioned. They have excellent power delivery though, awesome engines when they aren’t being problematic. That company also grenaded a lot of engines with poor timing tensioner design.
It lasted the lifetime of the money you had