Common Problems With The BMW B48 Engine (According To Owners)

The B48 is one of BMW's most well-regarded engines. It launched in 2014 as a replacement for the 241-horsepower BMW N20 and N26 engines and soon became a staple for BMW, powering cars and SUVs from nearly every part of its product line. The B48 engine is also used in non-BMW vehicles like the Morgan Plus Four, Toyota Supra 2.0, and 2025 Mini Cooper S. The 2.0-liter turbocharged inline-four gas mill is part of BMW's Modular B-Series engine family which includes three-, four-, and six-cylinder engines. That means it shares many similarities with the ever-popular 3.0-liter BMW B58 inline-six despite having two fewer cylinders and a corresponding smaller displacement. The two powerplants have the same bore (82 mm) and stroke (94.6 mm) while boasting a displacement of 500cc per cylinder. Both also have a closed-deck block designs and are fitted with direct injection technology as well as BMW's dual-VANOS variable valve timing and Valvetronic variable valve lift technologies.

However, the smaller B48's appeal lies primarily with its relatively affordable price and ability to keep fuel costs low while still being punchy enough, with up to 312 horsepower on tap. As with the B58, the B48 is versatile and has great tuning potential. There's also very little wrong with the engine in terms of reliability on the whole, as owners often praise it for being dependable. Despite the B48's well-earned reputation for reliability, owners have reported potentially expensive problems, particularly with the oil filter housing and some cooling system components.

Based on owner comments online, issues with the B48 engine oil filter housing are quite common. The unit often cracks and creates a coolant or oil leak around the 50,000 to 100,000-mile mark, according to a thread on the r/BMW subreddit. Because the oil filter housing is located underneath the intake manifold, you'll need to remove the manifold in order to reach it, making it difficult and potentially expensive to fix out of warranty. In a thread on Bimmer Forums, one owner sought advice on the DIY filter housing change, writing that their dealership was "going to charge me around $3k to fix it." On a positive note, owner feedback suggests that the oil filter housing units generally don't usually fail again once they're replaced.  Aside from the oil filter housing, some drivers have mentioned problems with the B48 engine's electric water pump and coolant return line hose. 

In a thread on the r/F30 subreddit, 330i owner u/engadinemaccas wrote, "It's not a matter of if they will fail, but when. They will fail and in most cases leave you stranded." Even with these common complaints, many owners report that the B48 remains as reliable as any modern BMW engine. But you can never be too careful when shopping around for a used B48-powered model. One way to avoid buying a BMW with a failing cooling system is to look for signs of leaking of coolant underneath the car. and check the oil and coolant for signs of fluids mixing. Even if there's no such indication, a good rule of thumb is to have a mechanic inspect the entire system to ensure that the coolant hoses and water pump are free from leaks and in good condition before you take the plunge.