[zobr]

Hello all,

Trying to convince my wife into getting a CPO 2020 330i with just 15k miles and her concern is long-term reliability. I've had a few BMW's over the years, most recently 2 340i's and just picked up a M550i. The B58's were super reliable, but will admit I don't know anything about B46/B48's. Is reliability similar? We plan on keeping for 6-7 years or until mileage reaches around 100k. No plan on tuning the 330i.

Is it even worth it to pick-up an extended warranty after the CPO ends? I know for sure I did on my M550i.

Thanks

[tturedraider]

The B46 is proving to be pretty much just as reliable as the B58. Personally, I don’t think an extended warranty is likely to be worth it.

I imagine your wife may not care much, but I would only have an M Sport 330i. The steering in the standard 330i is very Buick like. I can’t take it.

[zobr]

Agree! - I am def. making sure she gets an M Sport.

Originally Posted by tturedraider

The B46 is proving to be pretty much just as reliable as the B58. Personally, I don’t think an extended warranty is likely to be worth it.

I imagine your wife may not care much, but I would only have an M Sport 330i. The steering in the standard 330i is very Buick like. I can’t take it.

[Z K]

My wife has a 2017 F20 230i with the B46.

It has been problem free in the last 70k miles.

A engine fan sensor failed around 60k but that is not related to the engine itself. About $1k to fix at a local auto shop. The sensor is built into the engine fan and the whole thing needed to be replaced.

I DIY'd the spark plug change at 60k miles and do the oil changes every 8-9k miles. Brake pads were DIY at 60k miles as well. This is just regular maintenance.

[madpistol]

B46/B48 is supposed to be as reliable as the B58. The only reason it doesn't get as much attention is because it is the "normal" engine, while the B58 is basically a B48 + 2 cylinders and an extra dose of attitude.

[bavarianride]

I do bet on my B46(and the G20 330i 8AT) to last me 100k miles with minimal issues except tires + oil(7-8k miles) + air/cabin filters + spark plugs + tires + brake fluid. I don't track nor push the car, just regular DD(e.g. my factory brakes usually last past 90k miles).

My previous F30 N26 8AT last 80k miles and 8.5 years with just the above, ok I did pay $250 for a brake fluid + coolant service. That N26(even with the dreaded TC issue) just kept going. The car was sold with original brakes(with lots of life left)

These cars and engines are built well and can last with scheduled maintenance(don't need to go more frequent than what CBS/time-base requires)

And I don't have ESC on this G20, nor the previous F30, nor the E39 before F30. The E39 lasted past 100k miles and 12 years with around $3k-$4k lifetime out-of-pocket including tires + maintenance, the F30 less than $2k.

[zobr]

Anyone else?

Any problems with timing chains like the engines in the early F30?

[dod328430]

My 2013 328I had 94K trouble free miles, nothing but routine maintenance. Had a sensor go bad at 92k miles. kept it for 9 years, this is why I bought another one .

[billnchristy]

I think the dice roll with these cars is more on the electronic than the mechanical side, as long as maintenance is done of course.

[DrachenWerks Kfz-Technik]

My father passed me his G20 330xi with a B46TU in it. As an early 2019 model, Munich-built 3er, the car has been nothing but flawless with around 35k miles on it (it was bought at 19k ish, give or take). From what I know, the B48 and the B46 are essentially a B58 with two less cylinders since they all belong to the modular 'B' family of engines, so apart from the charge pipe I wouldn't really look at anything else. Of course, as the engine ages, the plastic bits and pieces in the engine would start to show their age but I wouldn't think much about it especially if you're not doing some serious performance mods like I will be. In general, BMW 3's, 4's, and 6 cylinder motors are very very good. And the B46/48 in my opinion are VERY underrated engines, considering that the tuning potential and the strength of these motors is very good.

[ersatz_lord]

As stated the b46/48 is very underrated. BMW has been using this engine in the M135i, Mini Cooper S, and JCW (including GP3) since 2014. I traded up from a 2015 Cooper S and I loved that car. I never had a single issue even after mods and tuning. I was pleasantly surprised at how well this engine performs in the 3 series.


The only issue is possible electrical gremlins like most modern cars using CANBUS. I had one in the Mini due to a faulty tail light panel.

[tturedraider]

Originally Posted by o935grf7

I don't know anything about B46/B48's. Is reliability similar?

It’s the same motor. The only differences are emissions related.

[billnchristy]

Oh and poopy motor mounts! I had a collapsed one on my x2 m35i and didn't even know it. BMW fixed it no issue of course, but apparently they fail on the normal b46/48 frequently too.

[Tysexton]

Hey guys new here, I am looking at picking up a 2021 330i, and have heard nothing but good things about them and the b48 reliability. What is the most miles you guys would by one used with. Currently I see a ton with about 30k miles, lease returns and wondering if that is a good idea. Please let me know 🙏

[zachBMW]

It’s pretty reliable (knock on wood) but i do believe long term it might encounter some issues.

Only reason im saying that is due to the amount of plastic used in the B46-48 engines. Lots of plastic components. In the long run something will probably take a dump on you but overall if you keep up maintenance and replace everything needed the car should last for a loooong time

1 year of ownership for me—things that have broken have NOT been engine related
-Needed whole new mirror
-Active grille didn’t want to open and gave a drivetrain malfunction. Cleared code and hasn’t been back since.

Best 4 cylinder all around on the market currently. Can even go FBO and make even more hp. And it will be reliable still if you go FBO

[zachBMW]

Originally Posted by Tysexton

Hey guys new here, I am looking at picking up a 2021 330i, and have heard nothing but good things about them and the b48 reliability. What is the most miles you guys would by one used with. Currently I see a ton with about 30k miles, lease returns and wondering if that is a good idea. Please let me know 🙏

I would go with one that has around 30k. i’ve seen some B46-48s with 100k miles already. Just spend the extra $ so you will have less miles on the car. Will last you longer in the long run. No point to spend 5k less on a car that would have roughly 20-30k more miles on it.

[bimmabum]

I've heard that the B48 is almost like a B58 with 2 less cylinders. apparently it also has the same forged internals as the B58 does. Someone correct me if i'm wrong

[djgreg1200]

I have a 2018 F30 with the B46 engine. Its been very reliable. I'm approaching 100,000 miles and the only things I've had to replace is the water pump for $1100 around 88K miles and the big one was the oil filter housing around 93K for a whopping $3100. The OFH is plastic so it will eventually fail. Just be prepared!!

[lagspike]

Note that the B46 application in 330i is not the highest output, with the same internals. Also, the same ZF8 is used in 340i, so the wear on it should be lower.

[QUiKSR20]

Motor / Trans? B48 & ZF are pretty bullet proof, Everything attached to them? Not so much.. 80-90k miles and your wallet will start to cry...
I Just spent $4500+ on my 2018 x3 ( b48 ) with 84k miles for many coolant system issues that should never happen on a car of this age.

- Cracked Oil Filter Housing + hoses that you should change $2500+
- Leaking Radiator + hoses that were brittle $2100+
- Leaking Turbo Coolant Return Line
- Leaking Overflow Cap

For a car barely over 4 years old and under 100k miles this is insane, these are not maintenance items and has been maintained meticulously.
Unfortunately I am putting this car for sale, Im not going to be the sucker that waits for the next two major coolant related items to strike which
are the Heater Control Valve and Water pump.

I cant imagine what it will cost when the water to air intercooler/intake manifold combo starts leaking.

Spending this kinda of money on repairs that shouldn't happen and is UN-acceptable, The car was dead reliable until 78k miles and has been downhill since..
It stinks because its a great looking and fun driving car but the reliability issues after 80k miles has left a real poor taste in our mouths.

The worse part is these issues are popping up on every B48/B58 so this will be wide spread on many diff cars.

[G20GotGame]

The B46/B48 engines (the 2.0L 4-cylinder turbo) in the 2020 330i are generally considered quite reliable, and they're an evolution of the B58’s design, which has been solid. While the B58 (in the 340i) gets more attention due to its performance chops, the B46/B48 has a good track record so far, with fewer issues reported than some earlier 4-cylinders from BMW.

In terms of reliability, if you're keeping the car stock and maintaining it properly, you should expect pretty good longevity. The B46/B48 engines are not without their quirks—some owners have seen minor issues like oil leaks, PCV valve problems, or the occasional fuel injector hiccup—but these are generally not widespread problems and can be caught early with proper maintenance.

The rest of the car, particularly the ZF 8-speed transmission and chassis, is pretty solid in terms of longevity, but like any BMW, it’s more about keeping up with the maintenance schedule—regular oil changes, cooling system checks, and addressing small things as they arise. By 100k miles, if well maintained, you should still be looking at a relatively reliable car, with the CPO warranty giving you some peace of mind for the first few years.

Bottom line: It’s a pretty good bet for a 6-7 year ownership period, and the B46/B48 engines, while not as bulletproof as the B58, are still a solid choice if you’re not planning on pushing it hard. If reliability is key, just keep an eye on regular service intervals, and you should be fine.

[QUiKSR20]

You failed to address all the coolant repair issues people are facing :

1 - Major Coolant System Repairs under 100k miles are not maintenance issues
2 - They are not cheap issues, they are issues that will cost you over $1500 each time

So while the motors/trans are bullet proof you will spend ( THOUSANDS ) on the coolant system after 85k miles.
There is no maintenance interval on your coolant system outside of changing fluid, These parts on most cars last over 200k miles.