High Mileage Guide

Mercedes Diesel High Mileage: OM651, OM642, OM654 Guide

Mercedes diesel longevity at 150,000+ miles. OM651 is the volume engine — reliable with EGR attention. OM642 V6 is exceptional. OM654 is the cleanest modern unit.

📅 Updated Aug 2026 👁 173 views

Risk:

5/10

💰 Est. cost: £700 –£3,000

⚡ Quick Summary

📌 At a Glance

Risk score: 5/10
Est. cost: £700–£3,000

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Fault case data for this topic is still being gathered
Last reviewed Aug 2026
173 readers so far

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How This Page Is Organised

This High Mileage Guide guide combines structured analysis — verdicts, risk scoring and cost ranges where we have enough data — with real fault cases pulled directly from MyCarFault's reporting database, so the guidance below reflects what owners actually experience rather than manufacturer specifications alone. Background and analysis come first, followed by the linked fault reports and related guides you can jump to directly using the links above.

Mercedes diesel engines have a strong reputation for high-mileage longevity when properly maintained. The OM651 four-cylinder, OM642 V6 and newer OM654 all have 200,000-mile capability, but each has specific maintenance requirements.

By Engine

Engine: OM651 (C220d/E220d/Vito)

150k Notes: EGR and swirl flap attention required. Otherwise strong engine.

Typical Issues 150k: Swirl flap actuator P2015, EGR fouling, injector seal leak on high mileage

Engine: OM642 V6 3.0 (ML350d/E350d/GL350d)

150k Notes: One of the most durable Mercedes diesel engines. Low fault rate.

Typical Issues 150k: Sprinter chain (different to car application), oil cooler on some variants

Engine: OM654 (C220d/E220d post-2016)

150k Notes: Best Mercedes diesel. Few reported issues in early data.

Typical Issues 150k: Too early for comprehensive 150k data — looking promising

Maintenance Critical

7G-Tronic fluid service every 60,000 miles — non-negotiable for gearbox longevity
EGR service at 80,000-mile intervals on OM651
Engine oil change every 10,000 miles max — standard interval too long for high mileage
Air filter every 20,000 miles on dusty roads

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Frequently Asked Questions

OM642 V6 examples have been documented at 300,000+ miles. OM651 is capable with EGR attention. OM654 appears to be similar.

OM651 vs N47: OM651 is significantly more reliable. OM651 vs N57: comparable. OM654 vs B47: both excellent.

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Important Notice: This page is based on owner reports, community discussions and MyCarFault case data. It is not an official manufacturer defect notice. Information about costs and reliability reflects community-reported experiences and may not apply to your specific vehicle. Always confirm diagnosis with a qualified mechanic before making repair or purchase decisions. MyCarFault makes no warranty as to the accuracy or completeness of any information on this page.