In 2003 began the delivery of new class 423 railcars in Frankfurt, in parallel, in August 2003, the first ET 420 were retired. As of 2004, Frankfurt ET 420 no longer received any main examinations; this was only in 2007 with 420 271 started when it became clear that the delivery of the last railcar due to registration problems would have to be postponed indefinitely. All Frankfurt vehicles were also from 2007 to 2008 for three million euros, a modernization in the interior, which included light gray instead of striped partitions and new upholstery in the current design. At the same time, the already quite advanced phasing-out was severely curtailed and henceforth focused on the railcars of the third construction series in order to be able to take at least the oldest vehicles out of service. Two railcars received the test LED headlights, but these could not prevail in Frankfurt.