Thermostat M654 for Mercedes-Benz

OE spec engine thermostat assembly, engineered for Mercedes Benz vehicles with the M654, also known as OM654, 2.0L turbo diesel. Restores correct warm up time and stable operating temperature, protects against overheating and weak 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 M654, OM654. Model year and chassis can use different housings, outlet angles and connectors. Some 4MATIC or emissions packages use unique part numbers. Always confirm by OE number.

Key Features:

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

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

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

• Durable materials: High temp plastics and seals resist glycol and thermal cycling.

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

Compatibility:
Common Mercedes models with M654, OM654 2.0 diesel, confirm by VIN or OE:

• C Class W205, W206 C220d, C300d where fitted

• E Class W213 E220d, E300d

• GLC X253, C253 GLC220d, GLC300d

• GLA H247, GLB X247 220d trims

• GLE W167 GLE300d in some markets

• Vito, V Class latest markets where OM654 is used
  Drivetrain: 2WD and 4MATIC where applicable. Markets vary, always match by VIN.

Options, engine or sensor variations:

• Standard OM654 thermostat with integrated housing and sensor.

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

• Emissions variants, SCR or AdBlue routing, may alter hose size and housing shape.

Typical OE reference families, guide only:
A654-200-… , A654-203-… 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 stays low or fluctuates.

• Overheating under load or in traffic.

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

• Coolant seepage at housing, dried crust around 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 M654, OM654 engine?
Check your VIN data card for the engine code. OM654 is the 2.0L four cylinder diesel used across many C, E, GLC and SUV models. Your VIN maps to the exact part.
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 that meets MB 325.x specification, mixed to the correct ratio.
Q4: What else should I replace?
Consider a coolant service, inspect hoses and clamps, and 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.