Thermostat W204 M274.910

OE spec engine thermostat assembly, engineered for Mercedes Benz C Class W204 models fitted with the M274.910 2.0L turbo petrol engine. Restores correct warm up time and stable operating temperature, protects against overheating and weak heater performance. Sold per unit, supplied with housing and sensor where applicable.

What this is / isn’t:
Included: 1× thermostat assembly

Important: Match by VIN and engine code M274.910. Late W204 models can use housings with different outlet angles and electrical connectors. Supersessions may alter plug style and hose size, always confirm by OE part number.

Key Features:

• Precise temperature control: OE matched opening temperature and flow for stable engine and cabin heat.

• Integrated housing and seal: Direct bolt on replacement to minimise leaks and comebacks.

• Correct sensor or actuator logic: Communicates with the ECU for accurate warm up and efficiency.

• Durable materials: High temperature plastics and elastomers resist glycol and thermal cycling.

• Exact fitment: Factory mounting points for a no mod install.

Compatibility:

• C Class W204, late production with M274.910, typical C200 or C250 petrol trims, verify by VIN.
  Drivetrain: 2WD and 4MATIC where applicable. Market years vary, confirm against OE.

Options, engine or sensor variations:

• Standard M274 thermostat with integrated housing and sensor.

• Year based revisions may change connector index and outlet orientation, verify before ordering.

• Market or emissions variants can alter heater outlet routing and hose diameter.

Typical OE reference families, guide only:
A274-200-… , A274-203-… with supersessions by year and market.
Always order by the exact OE part number on your vehicle or confirm via VIN.

Symptoms of a faulty thermostat:

• Slow warm up, temperature gauge low or fluctuating.

• Overheating in traffic or under load.

• Weak cabin heat, fault code P0128 or related temperature errors.

• Coolant seepage around the housing, dried crust at joints.

Installation notes, pro tips:

• Work on a cold engine, drain coolant below housing level.

• Replace the seal or O ring, clean mating faces, torque bolts evenly to spec.

• Refill with Mercedes approved coolant, MB 325.x spec, bleed the system thoroughly.

• Verify fan operation and hose temperatures on first heat cycle, clear stored codes after a road test.

• Inspect adjacent hoses, clamps and plastic tees for age related brittleness.

What’s included / not included:
✅ 1× Thermostat assembly with housing and seal, sensor or actuator if supplied
❌ Coolant, hoses, clamps, water pump, radiator, extra sensors, hardware

Q&A
Q1: How do I confirm I have the M274.910 engine in a W204?
Check your VIN data card, it lists the engine code. Your VIN will map to the exact thermostat part number.
Q2: Do I need coding after replacement?
Coding is usually not required. Clear any fault codes and verify operating temperature with a scan tool.
Q3: Which coolant should I use?
Use Mercedes coolant meeting MB 325.x specification, mix to the correct ratio for your climate.
Q4: What else should I replace?
Consider a full coolant service, inspect hoses and clamps, replace any brittle plastic fittings.

Why choose TOParts:
OE grade engine components for Mercedes Benz with precise fitment, correct specs and long term reliability, trusted by panel shops and independent Mercedes specialists across South Africa.