BMW M340d xDrive
Modular straight-six diesel with up to 340 hp in the M version. Extremely smooth and torquey; DPF and SCR catalytic converter are the main wear points.
Diesel Six
Modern inline-six diesel with excellent torque — refined and efficient.
Engine Weaknesses 5
EGR cooler can fail and allow coolant into the intake tract. Documented cases of engine damage shortly after EGR cooler replacement.
Symptoms: Coolant loss, white smoke, engine check light, overheating
Early B57 models (from about 2015/16) show chain elongation with rattling noises on startup. Timing chain replacement requires engine removal. Repair costs comparable to the N57. Significantly rarer from 2018 models.
Symptoms: Metallic rattling on cold start, especially at low temperatures; subsides after warm-up; in extreme cases engine stumble
Bearing damage occurs in the bi-turbo system at higher mileage. Turbine blades can break off and cause engine damage. Frequently encouraged by insufficient oil change intervals.
Symptoms: Whistling or howling under load; blue exhaust smoke; power loss; MIL; in extreme cases sudden power loss from turbo failure
The EGR valve cokes up with frequent short-trip driving and becomes stiff. Stumbling on cold start is characteristic. BMW carried out a voluntary service action.
Symptoms: Stumbling and hesitation on cold start until the engine warms up; power loss; 'Drivetrain malfunction' message; black smoke; EGR valve fault
NOx sensors and SCR dosing unit fail after about 100,000 km or through AdBlue crystallisation. Fault code 26F500 is typical. BMW repairs often cost 2,000–4,000 EUR as entire systems are replaced.
Symptoms: MIL with message 'AdBlue system faulty' or 'Emission system fault'; fault code 26F500; engine runs normally but warning persists
Vehicle Weaknesses 13
BMW recalled approximately 37,000 vehicles in 2024/2025 due to faulty 48V starter-generator bolting. Affected vehicles show battery charging problems and risk losing drive assistance.
On vehicles with the 48V mild hybrid system (320d, 330d, M340d), fault messages appear: 'Battery cannot be charged' or 'Do not continue driving'. Issue usually lies in the 48V sub-network.
The G20's electromechanical steering shows resistance around centre — small steering inputs feel jerky and require increased effort. BMW has prescribed full rack replacement as the fix.
Steering rack feels like a rolling weight when turning. BMW confirmed the defect after initially dismissing complaints. Replacement columns on 3–4 week lead time. Observed from as low as 600 km.
The curved display module shows sporadic static image interference. Warranty replacement at around 5,000 € list price. Occurs on vehicles with under 2,000 km.
Condensation through a defective vent membrane plus spontaneous cracks along inner seams with no impact marks. BMW refuses warranty for cracks. Design revision only with the 2025 model.
The adaptive suspension on the G20 is perceived as very harsh — every road imperfection is transmitted directly into the cabin. Sport mode barely differs from Comfort mode — consistent owner feedback.
Many G20 drivers report being repeatedly logged out of the My BMW app and ConnectedDrive. Software updates only fix the problem temporarily — a known systematic issue.
G20 owners consistently report severely increased paint sensitivity to stone chips. Windscreens show more damage after 10,000–20,000 km than older models after 100,000 km.
Knocking in the front suspension when rolling slowly over car park speed bumps. Steering rack identified as main cause — same weakness as the F80 predecessor.
Standard brake system squeals chronically — BMW states this is normal for M vehicles. Switching to road pads (Dixcel Type M, ATE Ceramic) resolves the issue permanently.
The stiff sport suspension transmits vibrations into interior trim. Most common location: the small glovebox below the light switch strip and dashboard speakers.
The M Sport brake system tends to squeal when slowing to a stop, caused by stick-slip behaviour of the performance pads. BMW classifies this as normal.