Mercedes Service A vs Service B: What Each One Actually Includes & What You Should Pay

The 30-second answer

Service A is the shorter annual service covering oil, oil filter, cabin filter, fluid checks and a vehicle health check. Service B is the longer 2-year service that adds brake fluid, air filter, spark plugs on petrol engines, and a deeper inspection. Your car tells you which one it wants next via the Active Service System on the dashboard — you do not have to guess. At an independent Mercedes specialist in London, expect £249–£349 for Service A and £349–£499 for Service B, depending on your model and engine. A main dealer will typically charge 40–60% more for exactly the same work using the same parts.

How the Active Service System decides

Every modern Mercedes has an Active Service System (ASSYST) that calculates service due dates based on actual driving conditions, not a fixed calendar. Short journeys, stop-start traffic and heavy loads accelerate service intervals. The system monitors oil quality via a sensor, counts cold starts, and tracks mileage. When a service is approaching, you will see a spanner icon and a message like "Service A in 30 days" or "Service A due now". The letter (A or B) tells you which service type is due. The number after the letter — e.g. "Service B4" — indicates additional items like brake fluid, spark plugs or air filter that are also due at that visit. Here is the key thing most owners get wrong: Service A and Service B alternate. After an A comes a B, then an A, then a B. If you bought a used car and the history is patchy, get the car plugged into Xentry — the diagnostic computer can read exactly when each service was performed and what is genuinely due next.

Service A: exactly what you get

Service A is fundamentally an oil change with checks. The core items are: engine oil drain and refill using the correct MB-spec oil for your engine (229.51, 229.52 or 229.71 depending on model), genuine or OEM oil filter replacement, cabin/pollen filter replacement, and a full fluid level check covering coolant, brake fluid, power-steering fluid, screenwash and AdBlue where fitted. The technician will also do a visual brake inspection measuring pad and disc thickness, check tyre condition and pressures, and reset the Active Service System via Xentry so the service indicator clears. Some garages include a short health-check report. At our workshop we also inspect the underside for leaks, check the auxiliary belt, and give you a written traffic-light report (green / amber / red) on everything we find. That is what a proper independent service should include. Be wary of a Service A quoted at £150 — at that price, either the oil spec is wrong, the cabin filter is being skipped, or the labour is being rushed. A genuine Mercedes oil filter alone costs £15–£25, and 6–8 litres of MB-spec oil runs £40–£70. With labour at £60–£90 per hour in London, a proper Service A cannot be done profitably for under £200.

Service B: the bigger service explained

Service B includes everything in Service A plus mandatory brake fluid replacement, an air filter change, spark plug replacement on petrol engines, and a much more detailed inspection. The brake fluid is one of the most important items — brake fluid absorbs moisture over time, which lowers its boiling point and can lead to brake fade under heavy use. Mercedes specifies brake fluid replacement every 2 years regardless of mileage. The air filter is also replaced at Service B, which is important because a clogged air filter on a turbo diesel like the OM651 or OM654 increases fuel consumption and reduces performance noticeably. On petrol engines — M274, M276, M177 — the spark plugs are replaced at Service B, typically every 4 years or 46,500 miles. This is not optional: worn spark plugs on a direct-injection petrol Mercedes cause misfires that can damage the catalytic converter (£1,500+ to replace). The Service B inspection list is significantly longer than Service A: the technician checks the condition of the exhaust system, suspension components, steering joints, driveshaft gaiters, all visible hoses and wiring, the fuel-tank ventilation system, the poly-V-belt, and all seat belts. At an independent specialist, this inspection is done with the same checklist a main dealer uses and takes around 45 minutes.

What "Service B4" or "Service A7" actually means

The number after the service letter indicates additional operations that are due at that visit. These are coded in the Mercedes maintenance system and your car will flag them on the dashboard. Common additional operations include: Brake fluid (every 2 years — included in every Service B), spark plugs on petrol engines (every 4 years / 46,500 miles), air filter (every 4 years in most cases), fuel filter on diesel engines (every 4 years / 46,500 miles), panoramic roof lubrication (every 3 years), and charcoal/cabin filter combination (every 2 years). When your car says "Service B4", for example, it means Service B plus operation 4. A good independent specialist will read the full list of due operations from Xentry before quoting you — you should never receive a quote that simply says "Service B" without specifying which additional operations are included. This is one of the most common sources of price shock: a main dealer quotes "Service B from £449" but the actual invoice with additional operations comes to £900+. We quote the full list upfront.

What is NOT included in Service A or B

This is where a lot of Mercedes owners get caught out. Neither Service A nor Service B includes automatic gearbox fluid and filter replacement. Mercedes describes the 7G-Tronic and 9G-Tronic gearboxes as "filled for life", which in practice means "filled until the gearbox fails after the warranty expires." Any experienced Mercedes technician will tell you the gearbox fluid and filter should be changed every 40,000 miles regardless of what the official schedule says. We have seen too many 7G-Tronic gearboxes fail at 120,000–150,000 miles because the fluid was never changed. A gearbox service at an independent specialist costs £250–£350 and takes 3 hours. The alternative is a £2,500–£4,000 gearbox rebuild. Also not included: transfer case fluid on 4MATIC models (should be done every 40,000 miles), diesel particulate filter cleaning (discussed separately with the customer if flagged), air conditioning service (separate job), and any repair work identified during the inspection. A good garage will separate "service items" from "advisory repairs" on your invoice so you know exactly what was routine and what genuinely needs addressing.

London prices: what you should actually pay in 2026

Here are realistic price ranges for an independent Mercedes specialist in London as of 2026. All prices include VAT, labour, genuine or OEM parts, and a digital service book stamp via Xentry. Service A (C-Class / A-Class / CLA / GLA): £229–£299. Service A (E-Class / GLC / CLS): £249–£349. Service A (S-Class / GLE / GLS / V6/V8): £299–£399. Service B (C-Class / A-Class / CLA / GLA): £349–£449. Service B (E-Class / GLC / CLS): £399–£529. Service B (S-Class / GLE / GLS / V6/V8): £449–£599. Add approximately £100–£180 for spark plugs on petrol engines and £60–£100 for a diesel fuel filter where applicable. Main dealer prices are typically 40–60% higher across the board. For comparison, a Mercedes main dealer Service B on a C220d can easily reach £680–£900 once additional operations are included. The work is the same. The parts are the same. The digital service book stamp is the same. The only difference is the coffee machine in the waiting room.