We often receive questions when someone is replacing an old part on their vehicle and the number on the old part does not exactly match the number on the new part. This is because of a part number supersession. Supersessions happen when a manufacturer updates or replaces an existing part number with a new one. There are many reasons for this including product updates and improvements, standardization and simplification, supply chain optimization, and end of life or obsolete parts.

Improvement

A common issue with the OM642 3.0L diesel engine in the Mercedes Benz is significant leaking at the oil cooler from the oil cooler seals. Mercedes has updated the oil cooler seals to improve performance and prevent premature failure. Although the seals are inexpensive, due to their location it is a very labor-intensive job. Mercedes has issued new improved seals with new numbers multiple times.

642-188-01-80  –> 642-188-04-80 –> 642-188-05-80 The last number is the current and only available version.

Standardization

Over time manufacturers may want to streamline production and reduce unnecessary complexity. Multiple parts which are identical or are nearly identical will be consolidated into one new part which will be given a new part number. 

Volkswagen has used the same rear brake pads in models since the 90’s. As newer models and platforms were introduced the brake pads were given new part numbers. Over time all those numbers get condensed down to one new part number. This reduces redundancy for manufacturers and ultimately cuts cost. 

Supply Chain Optimization

Automotive manufacturers do not make most of their own parts. Parts are sourced from companies that specialize in making parts for multiple car manufacturers. When we think of the top tier filter manufacturers companies like Mann, Mahle, Hengst, and UFI come to mind. Those companies have all made filters for auto manufacturers. Often an auto manufacturer will switch suppliers.  When this happens they may choose to give the part a new part number. 

End of life

Parts may no longer be in production as a new part but is still available as a remanufactured item. When VW supersedes a part number because it is a remanufactured item the part will be given a new number that ends in an “X”. Mercedes indicates and item is remanufactured by adding “80” or “88” to their standard 10-digit part number to make a new superseded 12 digit part number.

This may also happen as vehicles get older and demand for parts decreases. Volkswagen discontinued the air intake trap for BRM models. They superseded the part number and indicate that the new part is correct for the BRM and CJAA engines. For the older BRM engines it is not an exact part match and other parts must be replaced to complete the repair.

One more part number fact…

Not exactly a supersession, but Mercedes part numbers can be found with or without the letter A at the beginning. This indicates that is it a standard Mercedes parts. The letter B indicates that it is for a semi-truck. There is not overlap in the part numbers. With or without the A at the beginning it is the same part.