As successors to the ET423 S-Bahn multiple units, DB AG procured a total of 462 four-car electric multiple units of the 423 series starting in 1998. Unlike their predecessors, which had two bogies per car, the 423 cars were supported by a Jakobs bogie at the transitions. The 2350 kW four-car units reached speeds of 140 km/h. The first 190 units were equipped with GTO converters, which were housed in a separate container under the vehicle floor. The 423s are used in the Rhine-Main, Cologne, Munich, and Stuttgart S-Bahn networks. Loan operations have taken place in locations such as Hannover and Berlin.
| Key | Functions | Sound slots | Volume CVs | Volume values |
|---|
| F0 | Front light | | | |
| F1 | sound on/off | 1, 2, 18, 31 | 259, 267, 395, 499 | 255, 225, 120, 255 |
| F2 | air horn signal (high) | 3 | 275 | 200 |
| F3 | circulation pump | 22 | 427 | 110 |
| F4 | panto up/down | 27 | 467 | 110 |
| F5 | inside announcements (next stop) | 14 | 363 | 180 |
| F6 | acceleration/brake time, shunting mode/shunting speed | | | |
| F7 | curve squeal | 15 | 371 | 100 |
| F8 | AUX#1 | | | |
| F9 | compressed air let off | 9 | 323 | 40 |
| F10 | guards whistle | 10 | 331 | 80 |
| F11 | coupling | 8 | 315 | 25 |
| F12 | fault signal mtd | 16 | 379 | 80 |
| F13 | spring-loaded brake apply/release | 13 | 355 | 65 |
| F14 | train driver announcement | 7 | 307 | 170 |
| F15 | radiator fan on/off | 5 | 291 | 200 |
| F16 | open/close cab door | 12 | 347 | 120 |
| F17 | brake function 1 | 25 | 451 | 40 |
| F18 | auxiliary compressor | 32 | 507 | 40 |
| F19 | boarding aid for wheelchair users | 29 | 483 | 70 |
| F20 | disable brake squeal sound | | | |
| F21 | switch flange | 19 | 403 | 90 |
| F22 | special announcements | 20 | 411 | 180 |
| F23 | dead-man's vigilance device / enforced braking | 21 | 419 | 100 |
| F24 | compressor | 6 | 299 | 90 |
| F25 | sanding valve | 11 | 339 | 125 |
| F26 | soundfader | | | |
| F27 | passenger doors open/close | 24 | 443 | 220 |
| F28 | rail clank (4 x different selectable via SV10 value 0 to 3) | 17 | 387 | 80 |
Make sure that index CV31 is set to 16 and index CV32 is set to 1 before changing a volume CV.