The Mercedes OM642 is the 3.0L V6 turbodiesel found in the Sprinter 2500/3500, ML/GL/R-Class BlueTEC, E320 CDI, and Jeep Grand Cherokee CRD. Strong, capable engine - but plagued by a notorious oil cooler leak and emissions component failures.
The famous oil cooler seal leak is universal - intake must come off. EGR, NOx sensors, and swirl flap motors are also common. Bottom end is robust.
Oil cooler seals under the intake manifold harden and leak by 80-120K. Drips onto turbo and starter. Repair requires complete intake removal - the labor is the killer. Mercedes updated seal kit is mandatory.
View diagnosis →EGR valve cokes up with soot. EGR cooler cracks and lets coolant into intake. P0401, P2455.
View diagnosis →Pre and post NOx sensors fail (P229F, P220A). OEM-only parts. Triggers limp mode.
View diagnosis →Intake swirl flap motor lever and gears strip. Triggers P2008/P2009. Aftermarket steel levers are a permanent fix.
View diagnosis →DEF system heater and pump failures trigger countdown-to-no-start warnings. Mercedes part costs are extreme.
View diagnosis →Plastic turbo resonator on intake side cracks, causes power loss and hissing.
View diagnosis →Run a free AI diagnosis tailored to your exact engine. Get the most likely cause and repair estimate in under 30 seconds.
Run a Free Diagnosis100% free · No signup needed · Powered by NHTSA + AI
High-mileage 2009-2014 ML/GL/R BlueTEC without documented oil cooler + EGR service
2015-2018 Sprinter (improved seals, simpler emissions in cargo van trim)
Oil cooler service alone $1,800-3,500. Annual maintenance $800-1,200. Add NOx sensors and EGR cleaning every 100K. Total non-routine over 200K: $8,000-15,000 - this is a Mercedes diesel, not a Toyota.
If your Mercedes-Benz is throwing a check engine light, these are the codes most often associated with the problems above. Click any code for full diagnosis steps and typical repair costs.
The bottom end is. The accessories - oil cooler seals, EGR, NOx sensors, swirl flaps, DEF system - are not. Budget aggressively.
$1,800-3,500 at an independent. Mercedes dealer can be $4,500+. The seals are cheap - the labor (intake off) is the cost.
Bottom end will hit 300,000+ miles. Whether the owner stays solvent for 300,000 miles is a different question.
Bottom end yes. Plan on oil cooler service at 100K, EGR cleaning at 80K and 150K, and NOx sensors as needed. Many fleet operators run them past 300K.
Only with documented oil cooler service, recent NOx sensors, and an honest indy mechanic on speed dial. These are great trucks but expensive to keep right.