The BMW N53 engine was produced from 2006-2013. It is the last of a tradition from BMW that dates back to 1968. The naturally aspirated straight six has been a major component to BMW’s formula, which also includes rear wheel drive, and near 50/50 weight distribution. Based on extensive research, there are some notable common issues with the N53 but overall it is very reliable engine. Let’s go over the 4 common problems with the BMW N53.
History and Models
Fitted in BMW E9x 3series, E60 5 series and even the F10 5 series until 2011. The N53 replaced the N52 in most markets, except for notably the North American Market and Australia. These markets were excluded due to high sulfur content in the fuel. BMW was able to reduce fuel consumption in the N53 engine by adding direct injection and a nitrogen oxide storage catalytic converter. This catalytic converter required low sulfur content fuel to run properly. While most markets got the updated BMW N53, the U.S., Canada, and Australia continued to get the N52.
4 Common Problems with the N53 Engine
- Fuel Pump
- Injectors
- Spark Plugs
- Coil Packs
N53 High Pressure Fuel Pump (HPFP)
This is the first common and most prevalent issue to come up with the N53. High Pressure fuel pumps were such an issue when the engine first came out that BMW issued a recall on the engine. The N53 uses the same HPFP as the BMW N54, and these issues are well documented.
Symptoms of N53 HPFP Failure
- Long crank
- 1/2 engine light
- Rough idle
- Stuttering acceleration
When the high pressure fuel pump is failing it will not deliver enough fuel to the engine for proper operation. The lack of fuel flow is what causes long cranks, rough idling, and stuttering while accelerating. The 1/2 engine light may illuminate and the car will likely continue to drive until the HPFP completely fails and does not flow adequate fuel for the engine to fire.
Mileage for Failure
High pressure fuel pumps on the BMW N53 may fail at any mileage; many likely failed early on and were replaced under the recalls and extended warranty. In 2012/2013, after multiple attempts, BMW finally re-designed the HPFP which seems to have resolved the issues. If you are looking into purchasing a model with the N53, be sure to check the maintenance records to ensure the HPFP has been replaced either by recall or by the previous owner. Most N53 HPFP’s likely experienced failure early on and received the updated fuel pump, but there may be a few out there still running the original faulty part.
N53 Fuel Injectors
The N53 went from port injection to direct injection with Piezo injectors (similar to the BMW N54). With this change, came a learning curve and lots of changes and reprogramming to these parts. Though the BMW N53 and N54 both used direct injection featuring Piezo injectors the actual part number and injectors were different on each engine. Despite this difference, they suffered a similar fate with common failures.
Symptoms of N53 Fuel Injector Failure:
- Misfires
- Limp Mode
- Rough Idle
- Poor Fuel Economy
- Check Engine Light
Unlike the HPFP issue that does not flow enough fuel, the injectors typically fail by developing leaks and dumping extra fuel into the cylinders. This extra fuel causes misfires, rough idle, poor fuel economy and potentially check engine lights and limp mode.
If you do need to replace the injectors, do not buy them refurbished or used, and try to get them to match the same index. The newer fuel injectors that fixed the early issues have different indexes; it is important to note that different index fuel injectors can not be mixed on the same bank (i.e. cylinders 1-3 or 4-6). After replacement, they will need to be coded. Not replacing them properly can cause the engine to still run rough, which may lead into the next two issues. These 3 of the 4 common N53 problems have to do with misfires and rough idles.
Spark Plug Failure
Not a huge issue on the BMW N53, but something I saw come up several times with owners attempting to correct their misfire and rough idle situation. The spark plugs have been known to wear prematurely, causing misfires and rough idles. Leaking fuel injectors dump extra fuel near the spark plug tips causing premature wear. Also, if you have or had a valve cover gasket leak, there is a chance that oil has soaked into the plugs.
Symptoms of Old/Faulty Spark Plugs
- Rough idle
- Stuttering acceleration
- Loss of power & torque
- Reduced engine responsiveness
In addition to premature wear, spark plugs naturally wear down over time and become less effective or faulty, causing the same symptoms above. They should be replaced roughly every 40,000-50,000 miles, and are a cheap repair that can easily be completed by novice DIY’ers. If you know your spark plugs have not been replaced in that time frame it may be a good idea to knock out the repair as preventative maintenance.
Ignition Coils/Coil Packs
Another BMW N53 issue causing power loss, misfires and rough idles (same or similar symptoms as spark plugs). The coil packs are usually an overlooked issue. It seems most owners report this as the last item they replace after the injectors, and spark plugs to fix the misfires and rough idles. While it is difficult to diagnose with certainty, getting to the coils is relatively easy; they actually sit on top of the spark plugs and must be pulled out to replace the spark plugs. If the engine has over 50,000 miles (or if they have not been replaced in the last 50,000 miles), chances are the ignition coils may be faulty or under-performing.
Summary
Compared to other engines in the BMW lineup, I would say this engine is reliable and ready for a long life. Considering these 4 common issues with the N53, there are no major issues with oil leaking or with the cooling system which tend to end the life of the engine. Of course, older engines with high mileage may develop oil leaks or other issues as a part of standard wear and tear, though they are not overly common issues. A fuel pump may put you in limp mode, but will not retire the car to the junk yard. Same goes with for the injectors, spark plugs and coil packs.
Reliability score 1-4 with 4 being the worst: 1
BMW produced a fantastic engine to make its mark as their last naturally aspirated engine. Let me know what you think of the engine if you own one or your experience with it.
If you liked this post, check out our article on the N63.
I own a 528 ix drive 2010 and your are correct because it appears the engine is suffering from poor maintenance issues, it has about 200,000+ miles on it and im just beginning to feel the mileage. I have it at a BMW service center for diagnostic and im looking for economical ways to repair and upgrade this vehicle. Ironically I dont think im having any of the 4 issues here but I will be doing the replacements as it is extremely helpful information and im certainly glad I found this site. So far thou I will be needing a new transfer case, Vanos solenoid, But it seems to be typical 200k mile faults.
Hi Ulysses,
Thank you for the comment! That is impressive mileage, and goes to show these N53 engines have quite a bit of life in them. However, as you stated, that is definitely a point where things may start to catch up quickly. Any issues popping up at 200,000+ are fair game as that is quite a bit of wear and tear on any moving components. The HPFP and fuel injector repairs can be a bit pricey, so you may consider avoiding those repairs unless there is a noticeable issue or fault. Then again, it can’t hurt to tackle as preventative maintenance if it’s within the budget.
Best of luck getting your 528i xDrive running like it’s new again! We recently put about $12,000 into our 2007 335i with 113,000 miles to get it running like new again (though much of that budget included various upgrades and preventative maintenance). It’s definitely a rewarding experience to get your BMW back to where you want it.
Best Regards,
BMW Tuning Team
I own a 523i , 2011 with mileage 125.000KM. No issues at all so far. injektors and plugs replaced onde. The 6 cylinder engine runs smoothly and quietly and feels a little luxurious combined with the 8-speed automatic.
I hope the engine will keep on the good Work for years to come.
Hi Peer,
Glad to hear you’ve had a good experience with the N53 thus far. As you mention, the BMW inline-6 engines are well known for their extremely smooth operation and the N53 is no exception. They’re so smooth and subtle under normal driving, yet offer an aggressive feel when you push the car. Great balance all around.
Best of luck with your N53 for the years to come.
Regards,
BMW Tuning
My experience, I own a 530i M Sport, (N53 Engine, 2008 model)
35k (2010) – Injectors and coils replaced under recall
65k (2016) – Engine radiator and gasket housing around gearbox replaced (both leaking)
70k (2017) – HPFP replaced – Car basically broke down, limp mode.
80k (2018) – Drive chain replaced – massive job.
100k (2019) – MAF replaced
101k (2020) – Next week I’m having all 6 injectors, coils and plugs replaced with brand new parts.
All of the above under the recommendation of the BMW dealership having plugged the car in and checked repeated fault codes. In the end, I always used the same indy garage I’ve always used, Who is absolutely top-notch.
I’ve had nothing but ‘Engine Fault – Loss of Power’ issues with the car over the past 4 years. Each fix has made the car run smoothly for a certain amount of time (months). But the good old engine warning light has always come back to haunt me.
Now the car is rough, very rough on idle, rough-in the morning, rough after arriving to work (about 20 miles). Rough in traffic. and stinks of petrol! All the errors when plugged in are showing various injector misfires now. Hence the reason I’m having the lot replaced next week.
Funny thing is my mates say to get rid of the car. I can’t! Because iv spent so much on it, why would I want somebody else to benefit after replacing these past parts? Hopefully, I’ll get other 100k miles out of it.
Hi Jon,
Sorry to hear about the unfortunate issues. You’ve definitely had your fair share of the expensive ones. The N53 is a great engine, but is plagued with some similar fueling issues to the N54 with the fuel pump and injectors. The chain is an interesting one as that isn’t a terribly big issue on N53’s.
Nonetheless, we know the feeling of not wanting to get rid of your N53 after putting the time and money into it. We went down the same road with our N54 powered 535i. The car had a 2-3 year period with no breaks. Every few months a new, expensive issue popped up. Once we committed to replacing the water pump, expansion tank, fixing oil leaks, belt & pulleys, etc we were simply in too deep. Fortunately, it ended eventually. The car has been trouble free for the last 2-3 years. However, we must admit, it still does not run quite as well as our 135i and 335i which have been much better cars overall.
Best Regards,
BMW Tuning
I suspect the water pump next job actually. They did mention an error code relating to that too!!
Bloody cars.
Bimmerprofs…..google them it may be not system I have heard good reports
Thanks. Will give that a read!
Currently have a 325i m3 replica… car runs really rough only to find out my injectors where not coded properly…
Bank 1 running
Index 6
Index 11
Index 11
Bank 2 running
Index 6
Index 6
Index 6
2 index 6 injectors leaking… one on each bank so replacing with index 11’s hopefully will solve issue. Moreover the car is in very bad shape electronically however BMW Doctor (YouTube guy) has helped me out with DME CAS And all other electric issues. Car should like a dream after
My experience with N53b30 3.0 liter engine (BMW 325xi, 2008):
I bought it in February 2019 and the dealer said there is only one major issue – NOX sensor. I convinced the seller to decrease the price for 500 eur and bought it in hopes that I will replace it and enjoy driving. At the end, I have replaced NOX sensor, all 6 spark plugs, coils, all 6 fuel injectors, did walnut blasting, changed LPFP and filter, but the car still does not go as it should. I spent about 4000 euros over the year in replacement parts, but it still hesitates and feels like an old 1.8 volkswagen engine. Now, the indie told that loss of power and hesitation may be related to bad valve lifetrs, so I dropped it off for replacement of valve lifters and crankshaft bearing shells. I really hope it will solve the issue as I don’t have an idea what might be wrong with it. To be honest, I regret buying this car, because I never knew it can be so bad and expensive.
I have 2008 325i n53 manual and its a beauty. I bought it off my brother 14 months ago and he had owned it for 8 years! I did experience rough idle and stuttering throttle and loss of power after 1 month of owning the car but after i replaced the coil pack its ran buttery smooth since. One thing to be careful is cheap fuel. Give it some 95 or 99 octane and she sings. Next week ill do sparks and oil service myself. I love the linear power delivery and rowing through the gears
September 2018 I bought a 2008 325i e91 (3.0l) automatic with the N53 engine. When there’s nothing wrong with the car, I absolutely love it to bits. But, it’s needed a lot of work done… Sure, I was expecting some work was needed as the car had 230 000KM on it when I bought it. I’ve racked up around 25 000KM on it since I’ve owned it and this is what has been done so far:
– Full exhaust manifold replacement, cylinders 1-3 and 4-6, because the catalytic converter in both was shot. First the indy garage tried to burn the converters to clear any clogging but it was to no avail. Luckily I was able to find replacement parts from a shop here in Finland that sold used parts from wrecked cars, so I saved A LOT on parts. The “new” parts had less than 80 000KM on them. The work was very expensive though as the nuts and bolts keeping the old manifolds in place were completely corroded and melted into one. Also all the gaskets were ruined and had to be replaces.
– Nox sensor on bank1 after the manifold replacement.
– Gear lever replacement. The electrics on the gear lever were done for and the car couldn’t be put in to Sport Mode. Very cheap part from another wrecked car from ebay, Work was cheap as well as the replacement was very easy. Wire just clipped from the outside of the gearbox.
– Valve cover gasket was leaking so it had to be replaced, also the spark plugs and coils were then changed. This issue manifested exactly as loss of power, rough idle and such.
Other than that. I had to replace one loose trailing link and all door handles on the inside of the car because they had gone sticky as hell. I suppose someone had cleaned them with some chemical which ruined the rubber. Another big one that’s forthcoming is the profile-gasket on top of the oil pan… Again a cheap part but it takes some hours to do the work.
So all in all I’ve poured in about 4000€ on repairs in less than 2 years, not including new summer alloys and both summer and winter tires… So all in all around 5000€ so far. Can’t say I’m too happy about that.
I’m planning to keep the car as now at least I know what has been done and am not expecting any issues in the near future. Maybe in the spring it’s a good time to consider selling, as a rear wheel drive car with better than average power should be a desirable car for the summer 🙂
Brilliant thread and has confirmed some of my issues. I have a 2008 330i e93 with a meager 36k on the clock. I’ve only owned it for 1500k and am now finding faults. I’ve recently had misfire and engine light so changed plugs and found cylinders 3 4 and 5 to be black and wet. The injector indexing is strange as it has 5 index 9 and one index 3. Also found a crack in the Cylinder head cover right next to the oil top up hole. In the process of getting new parts from BMW but I’m a little surprised they have failed after such little use. Hopefully the fuel economy will improve as 22mpg is pretty poor.
Hi James,
Sorry to hear about your unfortunate issues with such a low mileage BMW. The different index injectors mixed definitely doesn’t sound great. It’s fine if the banks (cyl 1-3 & 4-6) had different injectors but you typically want all of the same index on one bank.
Sounds like a few of the injectors were leaking so I suspect you’ll pick up a little fuel efficiency once it’s all fixed up. Best of luck.
Best Regards,
BMW Tuning
Im fairly certain these engines need to be ran upto temperature. If its that old with such little mileage chances are you car hasnt had much chance to warm up to normal operating temps. Maybe im just old school
Its a very valid point, it does take a while to get warm and the oil temp takes a good 20+ min to get up. Do they typically take this long? This is my first 6 cylinder and my first Petrol for 10 years.
Well if you want you could change your oil to castrol edge 0w30 as mine was ran like that for 4 years which definitely made things heat up quicker and i never had any temps go above 105 even on hot days with very enthusiastic driving or if stuck in traffic. Now that my mileage is over 100k ive switched to 5w30 and im changing oil at half intervals just to be extra cautious. My advise is never go above 3k rpm until oil temps are up.
I have 2008 325xi N53 (3.0L, manual shift) with 160 000km/100 000 miles on it. I’ve owned it for 50 000km / 30 000 miles. Aside from replacing break housing,pads and disk on rear axel, so far no major renovations done.
During the last year or so, I’ve noticed one behaviour with the engine that slightly bothers me. Ie. is it an indicator of some part nearing its end of life.
Cruising with the car, nearing an intersection. Gas pedal lifted off for a good while and the car slowing down. Once at the intersection, still moving, revs below 1500rpm and now pressing the pedal in order to start accelerating again. about 1 sec after starting the acceleration, the engine stutters very briefly (0.1 sec) before continuing the acceleration normally.
In addition, now that we had cold weather (-18c/0F) here, the car didn’t start like on the warm weather. but the starting lasted several seconds (5+) where the engine got some revs, then lost the momentum and starter kicked in, got some revs, (rinse repeat) before finally starting up with dark petrol smelling exaust cloud. IE. last and previous winter it didn’t really matter how cold the weather was. Always started like in the warm weather.
I think the car hasn’t have spark plugs/coils/HPFS changed during its lifetime.
PS. The engine is absolute pleasure to drive, torque even at low revs, power that comes up nice and smoothly.
start with reading codes ; important for good diagnoses
and then the spark plugs (NGK) special for the N53 engine.
Worked for us ..
Dealerauto NL
I bought a 2009 E92 325i highline with the N53 engine on 54,000 miles in October 2020. Had it inspected twice and no issues apart from the oil pressure sensor was loose and the (I now know) dreaded NoX sensor fault. My local garage reconnected the oil pressure sensor and was fine, but the 30E9 nitric oxide catalytic converter, aging code wouldn’t go away.
I had a Noxem alternative sensor installed + adaptation done and it fixed the problem and improved the mpg from about 32mpg on a long run to 45mpg plus on a long run. It picked up a low pressure fuel pump 2AAF code after the Noxem was installed, but am told this is a shadow code so am leaving it.
Have also replaced the battery, spark plugs and one coil pack since buying. Overall its been a good buy, fun to rev car that looks really good with nice luxurious interior. Added an MMI unit to the CIC head unit for Apple Car play and it makes it feel a lot more modern.
Will probably look to do a muffler delete as the engine is sooo quiet and remap the car at some point in the future, although not essential at all.