We had a customer come in with a BMW 535i, N54 twin turbo engine with a check engine light on, whining noise on acceleration and loss of power. Checking the on board system for faults, it showed a code 30FF Turbocharger, charge air pressure too low. This code may be caused by intake or exhaust systems restrictions or leaks, waste gate valve wear, leak or binding, intercooler leak and after market accessories.
We checked for leaks and restrictions in the intake and exhaust systems and operation of the waste gate valve and they were fine. Testing boost pressure and the noise coming from the turbochargers showed that it was an actual turbocharger failure.
One of the reasons for early turbocharger failure on BMW is improper lubrication usually due to excessive intervals between oil and filter services, the oil level was good but the condition of the oil not that good. The customer was following the BMW condition based service (CBS) interval indicated by the vehicle, which is usually about 15,000 miles, we consider this excessive and suggest to reduce the interval to 5,000 miles. Another component that causes early failure for turbochargers on BMW vehicles is the condition of the battery! without any indication to the driver, like slow cranking or no starting if the battery state of charge is bellow a certain value the engine management system will not run the coolant pump to cool down the turbo after the engine is shut down.
The turbocharger replacement on this BMW is a big job, approximately 16 hours of labor plus a few thousand dollars of parts. It is a good idea to do the services more often to avoid the big expense.
