Engine Mercedes C43 AMG 3.0i v6 Bi-Turbo code M 276.823

In 2026, the Mercedes-AMG M276.823 remains one of the most balanced engines in the AMG lineup. This 3.0L V6 Biturbo powerplant is the heart of the Facelift (FL) W205 C43 AMG and represents the peak of the M276 evolution before Mercedes transitioned to the inline-six (M256) and four-cylinder (M139l) platforms.

1. Technical Specifications

The .823 variant is distinguished from the earlier .825 version by its factory-increased output and larger turbochargers.

2. 2026 Market Pricing (Estimated USD)

Because the C43 is a high-volume AMG, used engines are readily available, but the “Facelift” 390hp units command a premium over the 362hp pre-facelift versions.

• Used (Complete with Turbos): $7,000 – $9,500 (depending on mileage).

• Used (Long Block): $5,000 – $6,500.

• Remanufactured: $11,000 – $14,000.

3. Common 2026 Issues & Maintenance

By 2026, many C43s are hitting the 100,000 km (60,000 mile) mark. Here is what to look for:

• Camshaft Adjusters: A “rattling” sound on cold starts for 1–2 seconds is a sign of oil drain-back. Installing the check valve kit (a factory-recommended fix) is essential to prevent premature wear.

• Plastic Cooling Components: Like many modern German engines, the plastic coolant pipes and the “Y-pipe” can become brittle from heat cycles. In 2026, many owners are preemptively replacing these with aluminum aftermarket versions.

• Wastegate Rattle: The turbochargers on the .823 can develop a metallic rattling sound on deceleration. While often cosmetic, it can eventually lead to boost-control codes.

• Direct Injection Carbon: Despite being a newer engine, high-mileage units can benefit from walnut blasting the intake valves to restore lost throttle response.

4. Tuning Potential (The “Stage” Factor)

The M276.823 is famously “overbuilt.”

• Stage 1: With just a software remap, this engine easily hits 430–440 hp.

• Stage 2: Adding downpipes and an upgraded intercooler can push the engine to 470–480 hp reliably on the stock fuel system.

5. Installation Tip

If you are sourcing this engine for a swap, ensure it includes the High-Pressure Fuel Pump (HPFP). The facelift 390hp engine has a specific fuel mapping and hardware setup that is slightly different from the earlier 362hp models; swapping an earlier HPFP onto this block can cause lean-run conditions at high RPM.