Thermostat M274.920 for Mercedes-Benz

OE spec engine thermostat assembly, engineered for Mercedes Benz vehicles with the M274.920 petrol turbo engine. Restores correct warm up time and stable operating temperature, protects against overheating and poor heater performance. Sold per unit, variant specific as supplied with housing and sensor where applicable.

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

Important: Match by VIN and engine code M274.920. Model years and body styles can use housings with different outlet angles or electrical connectors. Emissions or AMG Line packages may change the part number. Always confirm by OE number.

Key Features:

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

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

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

• Durable materials: High temp plastics and elastomers resist glycol and heat cycling.

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

Compatibility:
Common Mercedes models using the M274.920, confirm by VIN or OE:

• C Class W205 selected C200 or C250 trims

• E Class W213 or late W212 selected E200 or E250 trims

• GLC X253 and C253 Coupe GLC200 or GLC250 where fitted
  Markets and years vary, always match by VIN.

Options, engine or sensor variations:

• Standard M274 thermostat with integrated housing and sensor.

• Supersessions by year may change connector style or outlet angle, verify before ordering.

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

Typical OE reference families, guide only:
A274-200-… , A274-203-…, 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 M274.920 engine?
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, mixed to the correct ratio.
Q4: What else should I replace?
Consider a 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.