Automotive recall events fell to a six-year low in the first half of the year, but the number of units jumped to a five-year high.

The recalls, led by electrical systems on both event number and unit volume, totaled 431 covering about 23½ million units, Sedgwick reported, citing National Highway Traffic Safety Administration data.

The electrical system-caused recalls in the six-month period were pumped up by one event that affected about 4.4 million units.

Overall recalls fell about 7% year-over-year, but unit volume surged about 112%, according to Sedgwick’s report.

Backup camera systems continued to be a major source of recalls, ranking second by volume at three million affected units, Sedgwick reported.

The firm pointed out that increasingly common over-the-air updates that often require no visit to the shop may collide with the snail mail-based consumer notification system that’s been used for years. It pointed out that regulators and Congress have been discussing more electronic notices.

Another change that could result from the automatic vehicle updates is reduced auto dealership involvement in recall repairs, Sedgwick said.

Last year, about a quarter of new vehicles sold in the U.S. were eligible for OTA updates, according to the report.