Mercedes A-Class 4th (W177) (2019–2023) — Key Programming Reference
- Difficulty
- expert
- Lishi / lockout
- HU64
Key fobs & transponder keys (2 variants)
| Key | Years | FCC ID | P/N | Chip | Freq | Battery | Blade |
|---|---|---|---|---|---|---|---|
| 315 MHz · IYZMS1 | 2019–2022 NA (US sedan; CA/MX sedan + hatch) | IYZMS1 | A1779052208 | Mercedes FBS4 BGA processor transponder (NEC/Infineon, encrypted) | 315 MHz | CR2032 | HU64 |
| 433.92 MHz · A1779057902 | 2019–2023 (EU + AU + JP + GCC export; 2/3-button RoW) | n/a | A1779057902 | Mercedes FBS4 BGA processor transponder (NEC/Infineon, encrypted) | 433.92 MHz | CR2032 | HU64 |
Programming procedures
What the job needs
- Add a key: 1 existing working key required.
- All keys lost: no existing working key needed.
- PIN / security code: No PIN — EIS + tokens.
- Online / server access: required — Cloud token req'd.
- On-board (no tool) sequence: not available — 2019-2023 W177 A-Class has no DIY onboard programming. Mercedes XENTRY / DAS3 dealer relearn requires SCN coding certificate. Aftermarket Add Key requires VVDI MB Tool + MFA2 EIS adapter + tokens OR Autel IM608 Pro II + IMKPA + G-Box3.
- On site: engine off · 13V+ aux + charger · Clear EIS + DAS DTCs.
- Bring: Photo ID + vehicle registration. Title strongly recommended for AKL. VIN cross-check.
Tool coverage
Documented for this case on: Autel IM608 Pro II · Autel IM508S · Autel KM100 · Xhorse Key Tool Plus · Xhorse Key Tool Max Pro · Lonsdor K518 Pro / K519 · OBDSTAR X300 DP Plus · AutoProPad G2/G3 · Advanced Diagnostics Smart Pro · Launch X431 IMMO Elite / IMMO Plus. Step-by-step menu paths for each tool are in the app.
Notes & cautions
- This chassis (W205 C-Class, 2015-2021) spans TWO FBS4 BGA key generations: 2019-2023 = FCC IYZ-MS1 (PN A2059053716, HU64 blade), 2019-2023 facelift = FCC IYZ-MS1 (HU64 blade). Both use Mercedes BGA processor transponder (FBS4) — most secure Mercedes IMMO before MBUX-era W206 IYZMS5I. Verify trim + production date — wrong FCC key will not pair even within W205 family.
- FBS4 BGA on this variant requires EITHER Autel IM608 Pro II + IMKPA + G-Box3 (bench EIS read for 2019-2023 full run on MFA2 platform) OR Xhorse VVDI MB Tool + W205 EIS adapter cable (different SKU than W203/W210/W221 — get the W205 cable, not generic). VVDI MB on W205 EIS = ~50-100 online tokens per password calculation; 1 token free daily from Xhorse Dolphin, additional purchased ~$5 each.
- AKL on FBS4 W205 typically requires EIS module removal + bench programming on older firmware; OBD-only AKL works on some 2019-2023 W205 builds via VVDI MB Tool. Verify chip generation before quoting — IYZ-MS1 (2019-2023) is more OBD-friendly; IYZ-MS1 facelift more often needs bench EIS read.
- AKL on this chassis erases all previously paired BGA keys. Bring minimum 2 new BGA Mercedes keys FCC IYZ-MS1. Wrong FCC means scheduled job cannot start. W177 keys are NOT cross-compatible with W176 (prior FBS3 A-Class).
- W177 AKL on 2019-2023 builds is OBD-only via Autel IM608 + IMKPA + G-Box3 or VVDI MB Tool + W205 cable. 2019-2023 builds (especially IYZ-MS1 facelift) increasingly require EIS module REMOVAL + bench programming — verify EIS firmware ID via XENTRY scan before quoting, or budget for bench job. Bench job adds ~1-2 hours labor + EIS reinstall + DAS3 reset.
- AKL erases EIS-paired remotes. Recovered old keys will not authenticate — customer must be informed. Verify trim before scheduling: C300 / C43 AMG / C63 AMG / C63 AMG S all share W177 EIS architecture, but AMG variants sometimes have stricter SCN coding requirements post-AKL (battery-disconnect re-init may need XENTRY).
Lockout
Door pick / decode: Lishi HU64 (CW).
20 verified sources · Last verified: 2026-08-10
Open full case in KeyAssist →Step-by-step tool menu paths, verified source links and video guides for this case are in the KeyAssist app — free to start, works offline.