BMW B38 1500cc 3-cylinder (118i 218i 318i 418i X1 18i X2 18i)
Problem: Heavy water vapor (white smoke) from the exhaust and excessive coolant loss.
You likely experience this because of the cracks in the turbo exhaust manifold that are chronic on B38 engines. B38 engines use a new-generation Continental turbo with a fully aluminum, water-cooled body. There is a water-cooling system in the manifold area to prevent extreme temperatures, and it uses your engine's coolant directly. As a solution, BMW states in service articles that the coolant must be a BMW-approved antifreeze. We always recommend checking your coolant and having it inspected by professionals so no air enters the system. The cracked manifold can be re-welded, but the definitive solution is fitting a new turbo manifold.
Problem: Drivetrain warning on the display, power-limited driving.
Generally, the reason for limited power on B38 engines is that the electronic wastegate in the turbo cannot calibrate itself. To confirm, the car is connected to a diagnostic device. This happens because, due to temperature difference, the metal part the wastegate (klappe) is attached to is blocked from moving.
Although BMW says the turbo must be replaced, our R&D shows the issue can be solved by removing the turbo, detaching the wastegate and re-adjusting it by hand — you do not need to replace the turbo.
A second cause: some cables in the engine's wiring run over the protective plastic toward the underside, where the knock-sensor cables are. These can be gnawed by street animals. If you get such a fault after diagnosis, we recommend lifting the car and checking underneath.
Problem: Momentary misfires and vibrations felt when accelerating.
This is an ignition-line issue. We recommend changing spark plugs every 10,000 km on B38 engines. Plugs not changed on time damage the coils and the electrical cables to them. If you go long without changing plugs, you experience momentary misfires. Changing plugs and coils usually solves it. If it persists after replacement, have the ignition-line wiring checked by a good auto electrician.
Problem: Excessive jerking on gear changes (ZF8HP).
If this happens on the 1-to-2 shift when the engine is cold, we recommend recalibrating the transmission with BMW's own diagnostic program. In some cases if calibration does not help, updating the transmission software removes the issue.
