Specs & OE references — 12V mini ISO 5-pin changeover relay (30/85/86/87/87a), green housing; with coil suppression (per OE design). Replaces A 002 542 23 19 / 0025422319, A 000 982 85 23 / 0009828523 (supersession), and A 002 542 76 19 / 0025427619; hardware marking often cross-referenced as 4RA 007 791-52.
Location & service tip — On W164/X164 the relay sits in the under-hood relay/fuse box (positions “G” and “I”). It’s commonly serviced with the air-suspension compressor; when the compressor is replaced, replacing this relay is recommended to avoid repeat failures.
Compatibility — W164 / X164 SUVs — Compatible with ML-Class (2006–2011) ML320 CDI/BlueTEC, ML350, ML450 Hybrid, ML500/550, ML63 AMG; and GL-Class (2007–2012) GL320/350 CDI/BlueTEC, GL450, GL550 (confirm by VIN/slot).
Compatibility — S-Class (W221) — Compatible with S-Class (2007–2013) including S600 and S63 AMG where used as multi-purpose / compressor / starter / horn relay depending on trim and option codes (verify by relay position and OE number on the original part).
Additional coverage — C/E/CLS lines — Also listed against C-Class W204 (e.g., C250 2012–2015, C300 2013–2014, C350 2011–2015, C63 AMG 2008–2015) and E-Class W212 (E350/E400/E550 2010–2016) where equipped; usage varies by circuit (multi-purpose).
Complementary parts (for bundled/related traffic) — Air-suspension compressor commonly paired with this relay on W164 (A 164 320 12 04) and on W221 (221 320 13 04 kit listings show pump+relay). Bundling the relay with the compressor helps ensure the compressor will engage reliably after service.