The S-code is used to identify what equipment level a unit had upon delivery. Such equipment could be standard on one market, but extra option on others.
Volvo don’t have information about S-codes for 1800 in their historical archive. We have to rely on spare part books and information from owners of 1800S, E and ES to decode the numbers. The list below is not at all complete and in some cases only assumptions based on photos in the 1800 register.
| S-code | Equipment | Model | Year | Market | Notes from the 1800 register |
| 1270 | ? | P1800S | 1963 | -S-code on the same line as ch# on the ID-plate | |
| 1320 | ? | 1800S | 1966 | -S-code on the same line as ch# on the ID-plate | |
| 5370 | Radiator in steel for the Nordic market | 1800S | 1968 | -Scandinavia | |
| 5564 | Fan with slip clutch and a number of minor parts including water pump no 419679-6 | 1800S | 1969 | ||
| 5577 | ? | 1800S | 1969 | -All 1800S 1969 | |
| 5589 | Cover for headrest Upholstery group 307 &317 Part no 693456-6 | 1800S | 1969 | -1800S 1969 California white (42) and Black (19) -Upholstery 307-500 -USA and France (import from US) | |
| 5590 | Cover for headrest Upholstery group 308, 318 Part no 692659-6 | 1800S | 1969 | -All red (46), all black upholstery (308-501) -Europe, USA and Panama | |
| 5591 | Cover for headrest Upholstery group 310, 320 Part no 692660-4 | 1800S | 1969 | -All dark green (94) or blue (99) with brown upholstery (310-557) -Europe and USA | |
| 5912 | ? | 1800E | Japan | -1800E 1971 -Japan and Australia | |
| 5950 | Multi blade fan | 1800E | 1970-72 | USA | -All 1800E 1970 -All California white (42) with red upholstery (327-625) -All with US spec. side indicators |
| 5951 | ? | 1800E | 1970-72 | USA & Canada | -Some with US spec. side indicators |
| 5952 | ? | 1800E | 1970 | USA | -All 1800E 1970 –All dark green (94) or blue (99) with brown upholstery -All with US spec. side indicators |
| 5956 | ? | 1800E | 1971 | USA | -All 1800E 1971 -All California white (42) with red upholstery (339-764) -All with US spec. side indicator |
| 5957 | US-specification | 1800E | 1971 | USA | -All 1800E 1971 -All dark green (94) or gold metallic (105) -All except 3 1800E with US spec. side indicators |
| 5968 | Headlamp insert yellow halogen light with casing and bulb Part no 1212892-2 | France | No cars in the register with that code. Strange with the same number below (from the spare part book) | ||
| 5968 | Safety belt Part no 673051-9 | 1800E ch 30001-37549 | USA & Canada | ||
| 6008 | ? | 1800E 1800ES | 1972 | USA | -US spec. side indicators |
| 6009 | ? | 1800E 1800ES | 1972 | ||
| 6010 | ? | 1800ES 1800E | 1972 | ||
| 6026 | Safety belt Part no 1221033-2 | 1800ES | 1972-73 | Australia | (only in combination with 5955) |
| 6040 | Exhaust pipe Part no 673224-2 | 1800ES ch#3070- | 1973 | USA &Canada | |
| 6042 | ? | 1800ES | 1973 | Australia | -All with roof mounted radio antenna (only in combination with 5955) |
| 6044 | ? | 1800ES | Australia | (only in combination with 5955) | |
| 6046 | ? | 1800ES | Only in combination with 5968 | ||
| 6073 | ? | 1800ES? | 1973? | ||
| 6077 | US-specification | 1800E& ES | 1972 | USA | -All with US spec. side indicators |
| 6078 | US-specification | 1800ES | 1973 | USA | -All 1800ES 1973 -All except a few with US spec. sideindicators |
| 6080 | Sun visor Part no L 1210418-8 Part no R 1210419-6 | 1800ES | 1972-73 | ||
| 6092 | ? | 1800ES | 1973 | (only in combination with 6115) | |
| 6106 | ? | 1800ES | 1973 | (only in combination with 6078) | |
| 6107 | ? | 1800ES | 1973 | -Great Britain, Australia and USA | |
| 6108 | ? | 1800ES | ? | ||
| 6115 | ? | 1800ES | 1973 | (only in combination with 6092) |
Combinations of several S-codes with links to cars on the 1800 register
5955, 6026, 6042
5955, 6026, 6044
5955, 6044
6008, 6077
6009, 6077
6010, 6077
6078, 6106
6078, 6107
6078, 6108
6092, 6115
5968, 6042, 6046