Fitment notes: AGM battery required for start-stop system; located in trunk; 48V mild hybrid system auxiliary battery
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Every control module on the 2021-2026 Mercedes-Benz S500 W223 — where it lives, replacement time, and what it takes to program a replacement. Modules marked dealer / factory tool won't work after a part swap alone — budget for programming.
Transmission Control Unit (TCU)4.5 hr R&Rsecurity gateway +1.2 hr▸ programming details
📍 Transmission housing, integrated valve body (9G-TRONIC)
🔧 Xentry Diagnostics + SCN online
⚠️ Requires transmission oil change, adaptation drive cycle, and SCN coding. Valve body removal necessary.
Electric Power Steering Control Unit (EPS)3.5 hr R&Rsecurity gateway +1.0 hr▸ programming details
⚠️ Simple adaptation required. Fuel tank does not need to be dropped for module access.
Radar Sensor Control Unit - Rear Right (RSU-RR)0.8 hr R&Rdealer / factory tool +0.5 hr▸ programming details
📍 Rear bumper, right corner behind cover
🔧 Xentry Diagnostics
⚠️ Short-range radar for blind spot and rear cross-traffic. Calibration required.
Aftermarket tool coverage varies by software version and vehicle build — treat "aftermarket tool" rows as "usually possible" and verify against your tool maker's coverage list before promising a customer. Spot a wrong location or hour? Tell us — corrections ship fast here.
Size-standard part numbers — verify your connector type before buying. Rear blades are model-specific; check the package's vehicle list.
Fuel economy figures are EPA data via fueleconomy.gov (median across matching trims). Performance figures are compiled estimates for the 2025 Mercedes-Benz S500 W223 3.0L I6 Turbo M256 and can vary by trim.
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Lexus & Toyota Mechanic · 20+ years.