I've recently found a white sludge-like substance on my oil filler cap and was hoping someone could explain what this is and if I need to worry about it. I've lost water in my filler tank. Also, there wasn't any sludge on the bottom of the dib stick. EML (Engine management light) is also on.

Unsure if this is a blocked oil breather filter and if so, where would this be in the engine for replacement part?

Any advice would be appreciated, thanks.

white sludge is a sign of water mixing with oil, most likely head gasket but I could be wrong

if you only use the car for short runs then the sludge on the cap is normal, this is because the engine never gets hot enough for long enough to burn off the condensation that forms naturally in the engine.

 

To get to the bottom of the engine light, you really need to get the car scanned with VCDS as it could be anything.