3 Potentially Surprising Reasons For A Check Engine Light On Your BMW
Like all modern vehicles, BMW uses the second-generation onboard diagnostic system (OBD-II) to track vehicle performance data and store error codes. This system relies on the concept of diagnostic trouble codes, often abbreviated as DTCs. A stored DTC will trigger the service engine light (also commonly referred to as the check engine light) to alert you to a problem.
Most people know this light primarily in the context of sensor failures and emissions problems. Monitoring the vehicle emissions system is one of OBD-II's primary roles, but it's not its only one. Modern BMWs track far more data, which may cause your check engine light to illuminate for these three potential issues.
1. Water Pump Failures
Most modern BMWs use electric water pumps instead of the belt-driven water pumps in many other vehicles. Electric water pumps offer a few advantages over older styles, and it's also easier for the car's ECU to monitor their condition. A problem with the water pump will typically trigger one of several proprietary DTCs, including 2E81 or 2E82.
A water pump failure will often create numerous other symptoms, including rapid overheating, potential loss of cabin heat, and limp mode. If you notice any of these symptoms along with your check engine light, pull your cover over and immediately shut it off. Driving an overheating car can cause serious damage, so it's a good idea to request a tow to an experienced BMW repair shop.
2. Turbocharger Issues
While BMW once manufactured primarily naturally-aspirated engines, most modern BMWs now feature turbochargers for added power and fuel efficiency. Turbochargers can substantially boost the performance of smaller engines, but they also add complexity and additional failure points. Issues with the turbocharger system can result in an underboost condition, potentially triggering DTC P0299.
Fortunately, this code doesn't always mean that your turbocharger has failed. Vacuum line leaks or electronic sensor failures are possibilities, along with various other issues. Since diagnosing a turbocharger system can be complex, it's a good idea to get your car to a qualified shop as soon as possible if you receive this trouble code.
3. Loose Gas Cap
Of course, not all check engine lights are due to serious problems. A DTC pointing to a problem with your evaporative emissions (EVAP) system can have numerous causes, but one potential failure point is the gas cap. A loose gas cap can allow small amounts of fuel vapor to escape, triggering an EVAP fault and turning on your check engine light.
If you receive an EVAP-related code, try tightening your gas cap and seeing if the check engine light disappears after a few drives. If not, you may need a BMW shop to investigate further since an EVAP failure will likely prevent your car from passing state emissions inspections.
Contact a company like All German Auto to find out more.