Earlier this month, we had a customer tow in his 2013 BMW X3 28i 2.0 liter. He said that he had been driving for 20 minutes and then a fuel supply warning light showed up on the dash. After that, the car went into limp home mode and then died. The customer could not restart the car. He called a tow truck and had it picked up. When the tow truck driver arrived, he was able to start the car and drive it onto the flatbed.
Once the car was dropped off, we connected it to the Intelligent Technical Service Application (ISTA). We ran a short test and pulled codes. We pulled the Electronic Fuel Pump Control Model (EKPS) fault 481B01 EKPS control voltage low. We then performed the test plan for the EKPS. We were unable to confirm a problem in the test plan, yet this is due to a temperature issue. The customer stated that the car went into limp mode after driving it for 20 minutes. Since the car is operating properly now, we drove it for 10 minutes and then let it idle outside for another 15 minutes. At this point, the car was fully warmed up. As we drove the car inside the shop, it went into limp mode. We then performed the test plan again and found that the fuel pump control module (EKPS) was shorting.
This X3 BMW has a high-pressure, direct-injected fuel system. When the fuel leaves the tank, it is being pumped out by an electric fuel pump. This electric fuel pump operates between 50 and 60 psi (it can pump as high as 100 psi). The electric fuel pump is considered the low-pressure delivery pump in the system. The whole system is controlled by the EKPS. The EKPS receives data from fuel pressure sensors in the fuel line. It then calculates the volume and pressure of the fuel that is delivered to the high-pressure fuel pump. The high-pressure fuel pump is mechanically driven by the engine’s camshaft. The mechanical high-pressure fuel pump is capable of producing 700 to 2900 psi. It operates normally between 1500 and 2900 psi. The purpose of this extremely high pressure is to deliver a very accurate amount of fuel into the combustion chamber.
After confirming there was a problem with the fuel pump control module, we did a little more digging. We then gained access to the fuel pump control module wire harness and made sure it was OK. Once we knew that the wire harness was OK, we were ready to replace the EKPS. Note: This X3 has approximately 100,000 miles on it. Most electric pumps start to wear out between 80,000 and 120,000 miles. Once the pumps wear out, they can draw secondary resistance and damage electrical components. We therefore suggested replacing the electric fuel pump along with the EKPS.
After the repair, we started to test drive the car. We would drive the car for 10 to 15 minutes and then let it idle outside before shutting it down. After multiple test drives, the car failed again. We then connected the ISTA and pulled a completely different code. We pulled a DME 11A002 high-pressure fuel rail pressure too low. After pulling the code, we ran the test plan. The test plan stated that the problem was with an incorrect reading from the high-pressure fuel sensor or a worn high-pressure fuel pump. We then replaced the high-pressure fuel sensor, but had the same issue. We then had to replace the high-pressure fuel pump.
After replacing the high-pressure fuel pump, we performed 100 miles of test drives. The car did not fail again. In conclusion, we feel that the Electronic Fuel Pump Control Model (EKPS) failed in part because of an old electric fuel pump. If a BMW with this fuel system sets an EKPS code and has more than 80,000 miles on it, it’s good to replace the fuel pump at the same time. Once the EKPS and fuel pump were replaced, the digital motor electronics (DME) decided there was not enough volume from the mechanical fuel pump. The mechanical fuel pump most likely was damaged due to low volume from the shorted EKPS. The lesson learned from this job is: test drive, test drive, test drive. Thanks for reading.
Matt Pataky owns Sunnyvale Foreign Car Service, 15 Pioneer Way, Mountain View. For more information, see sunnyvaleforeigncar.com.
