Dash oil guage
 

Looking to buy a 2003 boxster s.
Dash oil guage not working, what could be wrong

Bad sending unit or no oil.

In my experience on the late 986/996s ('01+), if you have oil in it, it is usually the instrument cluster because someone jumped it backwards when the battery was dead at some point in time. That will damage the cluster 100% of the time, and that is pretty much the only function that it will kill. I have repaired a LOT of 986/996 clusters because of this from all over the world. I usually start seeing them in spring when people get their cars going after their winter slumber.

I guess it is possible for the sensor to fail, but I haven't seen it. Usually the shops replace the sender first, then when it still doesn't work they call me. I am sure that the story the customer gets is that a bad sensor took out the cluster, which really isn't the case... Oh, and it is likely cheaper to fix the cluster than to do the sensor. So, if you decide to do the sender and it still doesn't work, send me a PM.

We have seen bad level sensors on multiple occasions.

oil sensor
 

where can i buy the sensor? will try it first, Price?

let me google that for you ;)
https://www.google.com/search?q=986+oil+pressure+sensor&oq=986+oil+pressu re+sensor&aqs=chrome..69i57j33.5295j0j8&sourceid=c hrome&ie=UTF-8

or this
http://986forum.com/forums/boxster-general-discussions/70645-oil-pressure-sending-unit.html

or this
https://www.pelicanparts.com/techarticles/Boxster_Tech/90-ELEC-996_Cluster/90-ELEC-996_Cluster.htm

information resource
 

Hope replacing the sensor works out for you! If not, I'd recommend giving https://www.instrumentclusterstore.com/repair_or_replace_instrument_cluster.htm a try. They specialize in all things clusters and are an excellent resource.