BMW 2 Series G42: B48, B58, S58, and B47 Engines—Problems and Owner Secrets, Explained
Quick Summary
The BMW 2 Series G42 (2021–present) is the successor to the F22 coupe, offered with rear- or all-wheel drive. The model offers 23 engine variants producing from 102 to 530 hp. The base gasoline unit is the B48B20 (220i, 135 kW), the top one is the B58B30 (M240i, 275 kW), diesel fans get the B47D20 (220d), and the M2 G87 comes with the S58B30, rated at 338 kW. The main takeaway: the B-series engines have shed many chronic problems of previous generations, but they carry their own weak spots you need to know about before buying.
The Problem
You climb into a used G42 and hear a strange noise at startup. Or you notice coolant residue around the oil filter housing. Or there’s condensation in the headlights. Is it cosmetic—or the first sign of an expensive repair? Here’s a breakdown of which problems actually threaten the B48, B58, S58, and B47, and how to prevent them.
Symptoms
- Noise at engine startup (possible timing chain stretch)
- Coolant or oil residue around the oil filter housing
- Moisture or condensation in the headlights and taillights
- Brake squeal at low speeds
- Strut clunk when driving at low speed
- Unstable engine idle
Causes
B48 is widely regarded as BMW’s best four-cylinder gasoline engine. The timing chain sits up front, which simplifies servicing; a closed oil circuit keeps pressure stable; and Valvetronic meters valve lift with precision. Unlike its predecessor, the N20, the B48 is free of chain-stretch trouble—its service life is significantly longer. The catch: the chain guides can break, and the plastic oil filter housing cracks over time.
B58 is a 3.0-liter inline-six with a closed-deck aluminum block, a water-cooled turbocharger, and dual injection (direct + port). That design lets it run high output without knock risk and solves the intake-valve carbon problem. The engine sounds fuller than its S55 predecessor, though without race-car aggression in the cabin.
S58 is a twin-turbo inline-six, 90% new compared with previous M engines. Forged pistons, a lighter crankshaft, a strengthened block with a closed cooling jacket. The S55’s on-track oil starvation problem is greatly reduced thanks to an active oil scavenging system.
B47 is a modular four-cylinder diesel, the direct successor to the N47, with the timing chain up front. A solid, mature diesel—though not without issues: short trips punish the DPF, and after 99,000 miles the injectors can begin to wear.
The Solution
Engine-by-Engine Diagnosis
| Engine | Problem | Mileage | Solution |
|---|---|---|---|
| B48 | Timing chain guide failure | 37,000 miles | Regular oil changes |
| B48 | Oil filter housing leak | 37,000 miles | Replace with a reinforced aluminum housing |
| B48 | Coolant return line crack | 43,000 miles | Replace the line |
| B58 | Oil filter disintegration | 19,000 miles | Immediate repair |
| B58 | Cracked oil filter housing | 62,000 miles | Replace with an aluminum housing |
| B58 | PCV membrane failure | 50,000 miles | Replace the valve cover |
| S58 | Oil cooler leak | 25,000 miles | Replace the cooler |
| S58 | Rod bearing wear | 31,000 miles | Replace the bearings |
| B47 | Timing chain stretch (2014–2016) | 75,000 miles | Replace the chain |
| B47 | EGR cooler leak | 62,000 miles | Recall campaign |
| B47 | Two-stage turbo failure | 81,000 miles | Replace the turbo |
Maintenance
For the B48: change the oil every 6,200–7,500 miles—the factory intervals are too long. Use BMW LL-01 or LL-17FE+ oil. Regular oil changes are the best way to prevent timing chain guide problems.
For the B58: change the oil every 6,200 miles and start checking the cooling system at 43,000 miles. At the first sign of an oil filter housing leak, swap it for the reinforced aluminum version.
For the S58: replace the plastic boost pipes with aluminum ones—it prevents them from coming apart under high pressure. Do an intake valve cleaning (walnut blasting) every 37,000–50,000 miles—despite the dual injection, carbon still builds up.
For the B47: confirm the EGR cooler recall has been performed—it’s a free procedure that can prevent a fire.
Prevention / Pre-Purchase Checklist
- Confirm the EGR cooler recall has been done (B47)—ask the dealer for the service history
- Confirm the main bearing recall has been done (S58, 2021 model year)—for the M2 G87 this is critical
- Inspect the headlights and taillights for moisture—even a little condensation can point to a problem
- Check the timing chain on early B47 engines (2014–2016)—a telltale startup noise means stretch
- Check the oil filter housing for leaks (B48, B58)—coolant or oil residue around the housing is a red flag
- Check the condition of the plastic boost pipes (S58)—cracks or deformation call for replacement
The Bottom Line
The BMW 2 Series G42 is a versatile model with engines ranging from 102 to 530 hp. The M240i with the B58B30 and rear-wheel drive is the ideal daily driver: 374 hp in a compact coupe, an attainable alternative to the M2. The M2 G87 with the S58 is for true enthusiasts: the most reliable M engine BMW has ever built, provided three conditions are met (replace the boost pipes, clean the valves, keep up with recalls). The B47 diesel is the economical choice for the highway, but for city driving the gasoline versions are better. The key move: before you buy, verify the recalls and the condition of the oil filter housing.