Enter your registration below. No email required — we identify your exact Mercedes engine, flag its known faults, and tell you whether a replacement is likely to be worth it.
No email required
Real UK enquiries
Vetted Mercedes specialists
Part of Engine Finders network
Enter your Mercedes registration and get your engine code, its known faults, and a repair-or-replace verdict in seconds — no account, no email, no obligation.
Try it below — this demo uses a sample of real fitment data to show how a result reads.
Demo tool — no email required to see a result. The live version connects to DVLA vehicle data and our full Mercedes fitment matrix. If the lookup can't confirm your plate, identify the engine manually with the fitment matrix or check the stamp using our engine number location guide.
No account and no email to see your result. Type the registration exactly as it appears on the V5C or the plate itself.
Your registration is matched against manufacturer build data to confirm the exact model, generation and engine — an OM651, OM642 or OM654, rather than just a badge. Where one badge spans two engines across a production run, we show both and ask you to confirm.
Engine code, known faults, real replacement cost data and a repair-or-replace verdict — then a route to a quote if you want one. Confirm the exact spec with the engine number location guide, or run the figures through the repair vs replace calculator.
This is one of eight free tools on the site — see also the VIN decoder, the engine value checker and the engine compatibility checker for related lookups.
The engine code is your vehicle's confirmed primary unit. For badges that span two different engines across their production run — some C-Class and E-Class diesels, for example — the lookup flags this and points you to the engine number location guide to confirm which you actually have before you commit to a replacement.
The verdict uses the same 70% repair-to-value framework published openly on our repair, replace or scrap framework page. It's a starting guide based on typical values for your model, not a substitute for your own vehicle's specific valuation — a low-mileage or well-specced C-Class W205 can justify a replacement that a tired example can't. Every result ends with a route to a quote from our vetted specialist network, so you can act on the verdict immediately.
The fault and cost data behind this tool is drawn from the same 2025 UK enquiry dataset behind every other page on this site — 24,650 quote requests handled across the full year [EM-VERIFIED]. Mercedes-specific volumes include 1,250 OM651 enquiries, 880 OM642 and 520 OM654 [EM-VERIFIED], which is what lets the lookup pair each engine with its most common failures and realistic replacement costs. Full methodology and limitations are set out on our Data Methodology page, and every figure is source-checked per our data verification standards.
Build and fitment data is cross-referenced against manufacturer records and independent parts suppliers, so the tool distinguishes an OM651 from an OM654 even where the badge alone is ambiguous.
Yes — a completely free Mercedes registration lookup online, with no email required to see your result. You only provide details if you choose to request a quote afterwards.
Very high for the primary engine fitted to your model and generation. For badges known to span two engines across their production run, we show both possibilities and recommend confirming against your engine number before ordering parts.
Use the full fitment matrix to identify your engine manually by model, generation and build year, or read the engine number stamp directly with our engine number location guide.
It covers the engines we hold UK enquiry data for — A-Class through S-Class, plus GLA, GLC, GLE and the Sprinter and Vito vans. If your vehicle uses a rarer unit, the fitment matrix will still place it.
Your result is free and immediate, always.
Where we're not certain, we say so and point you to the fitment matrix.
Every result routes to a Mercedes specialist who can confirm and quote.
No sponsors, no manufacturer influence.
Whatever your engine turns out to be, compare supply-and-fit quotes from our vetted Mercedes specialist network — or weigh the numbers first with the calculator.