The Albatross around Boeing’s neck, the 737 MAX airplane, has run into yet another problem.

On Friday, Boeing urged 16 of its customers to address a “potential electrical issue in a specific group of 737 MAX airplanes prior to further operations.”

The company said it wants those customers to check and verify if a sufficient ground path exists for a component of the electrical power system.

“We are working closely with the U.S. Federal Aviation Administration on this production issue. We are also informing our customers of specific tail numbers affected and we will provide direction on appropriate corrective actions,” the company said in a statement.

The 737 MAX jets were grounded worldwide after two crashes two crashes that took place within a span of five months left 346 people killed. Investigations into the accidents showed that a primary cause in each was a software function programme known as the Manoeuvring Characteristics Augmentation System (MCAS), which was intended to make the aircraft easier to handle. However, the MCAS, guided by only one Angle of Attack (AoA) sensor, kicked in repeatedly if that sensor malfunctioned, pushing the nose of the aircraft downward multiple times and leading finally in both accidents to a complete loss of control of the aircraft.