Engine Number Location — Mercedes-Benz Engine Number Guide

The Mercedes engine number is a unique identifier stamped onto the engine block – typically on a flat machined pad near the starter motor, on the cylinder head, or on the side of the block. The number is also encoded in the VIN (digits 6‑8) and on the vehicle data plate.

Stamped location varies by engine family – M272/M276 V6, OM651/OM654 four‑cylinders, and AMG V8s all have different positions
The full number includes the engine code (e.g., M272) followed by a serial number and often a suffix
Use the VIN or data plate as a backup if the block stamp is worn or inaccessible
Knowing the exact engine number is essential for ordering correct parts and verifying fitment
Last verified: February 2026

Full location guide, family‑by‑family details, common mistakes, and verification steps below.

What the Engine Number Tells You

The engine number is not just a random serial – it encodes the exact engine variant, production date, and specification.

Engine code prefix: M (petrol) or OM (diesel) identifies the fuel type and family.
Three‑digit number: The core family (e.g., 272, 276, 651, 642). This tells you the displacement, cylinder count, and basic design.
Suffix letters: Indicate features like direct injection (DE), turbocharging (LA), or specific emissions tuning.
Serial number: Unique to that particular engine; used for tracking production and recalls.
Production date: Often encoded in the serial number – can be decoded to determine if the engine is subject to known issues (e.g., pre‑2010 M272 balance shaft).

Having the full number allows you to check for technical service bulletins (TSBs), verify parts compatibility, and even confirm if a replacement unit is a direct match. For a detailed breakdown of the code structure, see our Engine Code Decoder.

Where to Find the Engine Number

There are three primary locations where the engine number is recorded on a Mercedes‑Benz vehicle.

Engine block stamp: The definitive location – a stamped metal pad. The position varies by engine family (see the table below).
Vehicle data plate: Located on the driver's side B‑pillar (door jamb) or inside the engine bay on the strut tower. It lists the engine code and often the full engine number.
VIN (Vehicle Identification Number): Digits 6‑8 encode the engine variant, but not the full serial. However, it can be cross‑referenced with Mercedes databases to retrieve the full engine number.

If the block stamp is unreadable due to corrosion or wear, the data plate or VIN are reliable backups. For older vehicles (e.g., W124, W210), the stamp may be on the cylinder head rather than the block.

Engine Number Location by Engine Family

Different Mercedes engine families have the stamp in distinct positions. The table below covers the most common UK‑market engines.

Engine Family	Typical Stamp Location	Notes
M272 (V6 petrol, 3.0‑3.5L)	On the right‑hand side of the block, near the starter motor, just above the sump line	Often partially hidden by the starter; may need a mirror to read
M276 (V6 petrol, 3.0‑3.5L)	Similar to M272, but on the left‑hand side (viewed from front), behind the alternator	Newer design; stamp is on a flat pad, easier to access
OM642 (V6 diesel, 3.0L)	On the front of the block, near the oil filter housing, or on the side below the injectors	Some models have it on the cylinder head; check both
OM651 (4‑cyl diesel, 2.1L)	On the left‑hand side of the block, behind the high‑pressure fuel pump, visible from above	Often stamped on a machined surface just below the cylinder head
OM654 (4‑cyl diesel, 2.0L)	On the right‑hand side of the block, above the starter motor	Modern engine; stamp is clearly visible with a torch
M157 (V8 AMG, 5.5L)	On the rear of the block, near the transmission bellhousing, or on the side under the exhaust manifold	Hot‑vee design makes it harder to access; often requires removing heat shields
M178 (V8 AMG, 4.0L)	On the front of the block, behind the water pump, or on the side near the turbochargers	Modern V8; stamp is on a visible pad but may be obscured by pipes
M270 (4‑cyl petrol, 1.6‑2.0L)	On the front of the block, near the timing cover, or on the side behind the alternator	Used in A‑Class, B‑Class, CLA; access from above
M274 (4‑cyl petrol, 2.0L)	On the right‑hand side of the block, near the starter motor (similar to M272 but smaller)	Successor to M270; slightly different position
OM646 (4‑cyl diesel, 2.1L, pre‑OM651)	On the left‑hand side of the block, behind the EGR valve, or on the cylinder head	Older design; may need to remove engine cover

These locations are based on Mercedes‑Benz workshop manuals and verified by independent specialists. Always consult the vehicle‑specific manual if unsure.

Notes & Caveats

Facelift and model‑year variations: Even within the same family, the stamp location may shift slightly. For example, early M272 (pre‑2007) had the stamp on the left, later on the right. Always confirm with the vehicle's specific manual.
US vs UK specifications: American‑spec engines may have additional emissions equipment that changes the stamp location; UK/EU engines follow the positions listed above.
Engine replacement: If the engine has been replaced, the block stamp will belong to the replacement unit, not the original VIN. Always verify both the block stamp and the VIN to avoid mismatches.
Corrosion and wear: Stamps can become faint on older vehicles, especially in road‑salt areas. Use a wire brush or chalk to make the characters more legible.

Common Mistakes

Confusing the VIN engine code with the full engine number: The VIN only gives the engine variant (e.g., OM651), not the full serial. You need the block stamp for the complete number.
Assuming all engines of the same family have the same stamp location: As noted, revisions and different vehicle platforms can move the stamp. Always double‑check.
Ignoring the data plate: The data plate is the easiest place to find the engine number without getting your hands dirty – but it must match the block stamp. If they differ, investigate.
Ordering parts based solely on the engine code from the VIN: The full engine number includes a suffix that can indicate different injectors or timing chain kits. Using only the base code may lead to incorrect parts – see our Engine Code Decoder for more detail.

How to Verify Your Engine Number

Follow these steps to confidently identify your engine number:

Check the vehicle data plate – it's the quickest method. Open the driver's door and look at the B‑pillar; the engine number is often printed there.
Locate the block stamp using the table above. Clean the area with a rag and use a torch to read the characters. If they're faint, rub a crayon or chalk over the surface to highlight them.
Cross‑reference with the VIN – use our VIN Decoder tool to pull the factory engine variant and compare it with the stamped number.
If the numbers don't match, the engine may have been changed. Contact a specialist or use our Diagnostic Wizard to help identify the actual engine fitted.

Having the correct engine number is critical for ordering parts, checking service bulletins, and making informed replacement decisions – which is why we maintain this reference as part of our data methodology.

Why This Specification Matters

The engine number is the single most important piece of information for any repair or maintenance task. It dictates which oil filter, timing chain kit, injectors, and even which engine oil grade (viscosity and specification) to use. Ordering the wrong part because of an incorrect or missing engine number can lead to misfits, premature wear, or catastrophic failure.

For example, the OM651 diesel engine has multiple revisions – early versions have a known balance shaft issue, which is corrected in later variants. Knowing the exact engine number allows you to check if your engine falls within the affected range and plan preventive maintenance accordingly, as detailed in our OM651 balance shaft failure page.

Similarly, the M272 V6 petrol engine is notorious for the balance shaft timing chain sprocket failure; identifying your engine as M272 (especially pre‑2010) alerts you to monitor for symptoms. This guide is not just a reference – it's a diagnostic starting point.

Related Specifications

Engine Code Decoder →

Understand the meaning of the code prefix and suffix.

Mercedes Fitment Matrix →

Which engines fit which models – essential for replacements.

VIN Decoder Tool →

Decode your VIN to get the factory engine variant instantly.

M272 Oil Capacity →

Oil spec and capacity for the 3.5‑litre V6 petrol.

OM651 Oil Capacity & Spec →

Correct oil specification for the 2.1‑litre diesel.

Failure Rate by Engine →

Data‑backed reliability of each engine family.

Frequently Asked Questions

Where is the engine number on a Mercedes‑Benz?

It is stamped on the engine block (location varies by family) and also printed on the vehicle data plate (B‑pillar) and encoded in the VIN (digits 6‑8).

How do I find the engine number on a Mercedes OM651?

On the OM651, the stamp is typically on the left‑hand side of the block, behind the high‑pressure fuel pump, visible from above. It's on a machined surface just below the cylinder head.

What if the engine number is unreadable due to rust?

Clean the area with a wire brush and use chalk or a crayon to highlight the characters. Alternatively, the data plate and VIN are reliable backups.

Does the engine number change if the engine is replaced?

Yes. The new engine will have its own unique block stamp. The VIN remains the same, so always verify that the block stamp matches the documentation.

Can I find the engine number without lifting the bonnet?

Yes – the vehicle data plate on the driver's door pillar and the VIN (using our decoder) provide the engine variant, but for the full serial you will need the block stamp.

Why does the engine number matter for ordering parts?

Different revisions of the same engine family can have different components (e.g., timing chain guides, injectors). The full engine number ensures you get the exact parts for your specific engine.

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Verified DataCross‑checked with Mercedes‑Benz workshop manuals and specialist workshops.

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Last Verified February 2026Regularly updated to reflect the latest engine codes and revisions.

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15+ Vetted SpecialistsReal‑world insights from Mercedes specialists across the UK.

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100% IndependentNo manufacturer or dealer bias – pure technical reference.

Engine Number Location — Mercedes Engine Number Guide