Common BMW Problems
Oil leaks (ie. Oil filter housing gasket, valve cover gaskets)
Oil leaks occur more frequently on vehicles with over 60,000 miles. A common cause of BMW oil leaks are the valve cover gaskets The oil pan gasket is also a likely cause of a BMW oil leak, and will require removal of the front suspension in order to be replaced. If none of these are at fault, the timing cover gasket or oil filter housing gasket may be the issue if a leak is coming from the left side of the engine.
Power steering leaks (ie. Power steering reservoir, power steering hoses)
If there is power steering fluid on the ground or you hear a screeching noise while turning, it is likely that you have a power steering leak. Increased difficulty turning the wheel accompanied by a groaning sound is an indicator of a leak from the power steering hoses, and you should have them replaced as soon as possible to eliminate a more serious repair. To see if fluid is leaking from the fluid reservoir, check the reservoir for abnormally low fluid levels. In addition, check to see if the filter located at the bottom of the reservoir is clogged, causing restricted flow of fluids to the power steering fluid pump, requiring a reservoir replacement.
Coolant leaks (ie. Radiator, expansion tank, coolant hoses)
Coolant leaks from your vehicle's radiator are often the result of a radiator cap that is loose or broken. The radiator cap regulates the pressure in the radiator, and a loss of pressure from a faulty cap can cause a leak to occur. If you notice white smoke coming from the exhaust, there may be a leak involving the expansion tank, which can develop cracks with age, or the coolant sensor within the tank. When coolant is visibly leaking outside the vehicle or it seems like coolant is leaking from the water pump, often times there is a leaking from a broken coolant hose or faulty coolant pipe seal.
Fuel pressure concerns (ie. High pressure pump malfunction)
Fuel pressure issues may involve your vehicle sputtering when you accelerate from idle or drive at higher speeds caused by the incorrect amount of fuel being spray into the combustion chamber, making the engine stall. When the high pressure fuel pump fails, it is not able to spray a constant stream of fuel into the engine. Don't ignore the sputtering caused by this engine inconsistency, because if a repair is put off for too long, the engine will eventually fail to turn over.
Check engine light
The most common issues that can make your BMW check engine light illuminate include:
Oxygen sensor - can cause a decrease in gas mileage and increased emissions
Gas cap - if loose or cracked can signal a leak in the Evaporative Emissions System
Catalytic converter - reduces exhaust gases and also affects gas mileage.
Note that if the light comes on and you are notified of a PO420 code, or "cat code", you most likely have a faulty oxygen sensor, an exhaust leak, or abnormal fuel mixture, but probably not an issue with the catalytic converter.
"Reduced power" message on instrument cluster
The "Reduced Engine Power" warning light is meant to notify drivers when there is a serious problem with the transmission or other components of the engine. The most common issue when this light comes on is a defect in the throttle control system, but other issues may include a defective throttle position sensor, oxygen sensor, accelerator pedal position sensor, or damaged wiring. When the engine has reduced power, the vehicle may not be capable of reaching speeds over 20 miles per hour, and sometimes may be in need of a software upgrade.
Brake lights often come on at the same time as a result of wheel speed sensor failure, as they are the ABS system components exposed to the greatest amount of wear. If the ABS light is still on after all repairs have been completed, there may be an issue with the instrument cluster itself, but more likely than not there is still an issue with the ABS module. To reset the instrument cluster and check for issues, disconnect the battery for an hour and see if the light has gone out once it's reconnected.
In addition to the speed sensor, any basic problem that causes the rear brakes to apply too quickly can activate the ABS. These issues may include cracked rear linings, oil-contaminated linings, weak brake return springs, or a faulty proportioning valve.
The service indicator light on your BMW will illuminate periodically as a reminder that your vehicle is in need of service, including routine oil changes and other simple maintenance. It is possible to reset the light yourself if you perform your own oil changes, or if the light refuses to go off after your vehicle has been serviced.
To Reset: Hold down the odometer reset button and simultaneously put the keys into the ignition and turn them once to the accessory position. Keep holding the reset button until the indicator light flashes and the word "Reset" is displayed. Next, release the button and press and hold it one more time. Once it is released, five green LED lights will appear showing that the system was reset.
Since the BMW cooling system only holds a small amount of coolant, it is important to have your vehicle repaired shortly after it shows signs of overheating. Generally, coolant parts should be replaced every 60,000 miles to avoid issues.
If your vehicle does overheat, their are a few different possibilities for the cause of the problem. First, a failing coolant reservoir or radiator can result in pressure issues that prevent coolant from reaching the engine, which then overheats. In addition, the engine fan may need a repair or replacement so that air continues to flow properly through the radiator to prevent the vehicle from overheating at low speeds. A defective thermostat that limits the flow of coolant to the radiator is also an option if your engine is overheating.
Steering wheel shakes/pulsation while braking
Warped rotors are a frequent cause of vehicle pulsation while braking. Your steering wheel may also shake if your rotors are worn, as the wheel vibration is transferred to the steering column through the front-end components that the brake calipers are bolted to. If your rotors are only slightly warped or worn, you may be able to get away with only having them straightened out. However, if they are new or have just been replaced, they may not have been properly mounted to the axle.
Window doesn't go up or down/ crunching noise while moving windows
There is most likely a problem with your power window regulator. Issues with the power window regulator mechanism can cause the windows on your vehicle to refuse movement. An electrical problem with the window regulator can cause the window to roll up or down slower than it should, but before assuming the regulator is the issue, make sure the window switch itself is inspected, as this is also a likely cause of window failure. If you hear clicking or grinding when the window is rolled up or down debris may be trapped between the window and the motor assembly, which can cause the regulator to work harder than it should to move the window.
Electrical concerns (ie. battery keeps dieing)
Often poor battery life is caused by parasitic drain caused by electrical components in your vehicle that continue drawing current after it is turned off. While some drain is normal (i.e. for the clock, radio, and security alarm), electric problems such as a faulty seat control module can result in too much battery drain when your vehicle is not running. Service information published by BMW shows a timeline for current draw after vehicle shutdown. After an hour, the parasitic loss should be less than or equal to 30 milliamps, or 0.0s of an ampere hour.
An alternator with a faulty diode that causes the circuit to charge even when the engine is off can also cause excessive battery drain.