Unraveling date codes on fuel filters and other par

How old is that fuel filter?  Should it be changed?

We ask that question every time a fuel injected car comes into our shop for a check-over.  Modern fuel filters are generally metal, so we can’t see inside.  That leaves us one evaluation option – age.

Most carmakers recommend fuel filter replacement on a three to six year interval.  How do you know when that time is passed, if you have no records?  The obvious answer  . . . read the date code from the filter itself.

If you have a Bosch filter (Robison Service is a Bosch authorized service center) you can find and decode the date stamp.  Here’s an example.

The part number – 0 450 905 295 is the biggest and most obvious number, as it should be.  The number in the oval (957) is the factory code.  The date code is the dot matrix printing at the edge.  In this case the code reads 863.13.1.06

We turn to our Bosch date code index to decode the year and month, 863:

According to our chart, this filter was made in March of 1998.  The next number, 13, tells us the date of manufacture.  The final numbers are plant specific, identifying a particular assembly line or location.

Seeing this part on a 1999 Rolls Royce we can say with some confidence that it’s the original filter.

What if the date code is newer?  How closely can we date a filter on a car from these numbers?  The answer – not too close.  A check of brand new filters from Bentley revealed date codes from April 2010 to June 2011 in August 2012.  That suggests filters for high end cars may sit in warehouses several years before being installed.

A check of date codes on higher volume Mercedes/BMW/Audi filters shows much quicker turnaround.  The filters on their shelves left the factory 2-4 months previously.

So what’s the rule of thumb?

In our shop, if we are looking at an exotic or rare car, I’d allow 2 years for a filter to sit before being installed, and I’d expect it to last 10 years in light use.  So I’d replace any filter whose date code was more than 12 years in the past. 

With a more common car, I’d look to replace any filter whose date code was more than six years in the past.

These are the rules we apply at Robison Service, but your mileage may vary.  Obviously a load of bad gas can clog even a brand new filter, and some filters that are a decade in service are as clean as when they were installed.

Till next time

John Robison