What does it mean when the check engine light is constantly on and the cruise control light is flashing?

Take it in to have any codes read from the ECM. This would point you in the direction of a repair.

Your 8 yr old 2.5i will getting myriad CELs in the next few years, so I'd invest in a small $40 ACTRON or similar OBDII scanner. Most of the codes will be the infamous PO420 "cat conv insufficiency", which most folks ignore unless Subie cuts you one for free. Similarly, wet weather will cause idiosyncratic misfires codes, so dress the wires away from the coil and intake manifold structures..... Others, like O2 VVT sensors indicate necessary repairs, however. The cc blinker is just a Subie habit of connecting an added warning light to the CEL system. Once you clear the CEL the cruise will operate normally again. Have fun. Oh...drain and refill your autobox if you've ignored that.

Our 2013 Impreza manual had the exact issue along with the ESC light. Turned out to be an electronic switch problem that the dealer fixed quickly; it was still under warranty at the time.

There are a lot of these reported on the internet. If the scanner comes up with variable valve timing problem try the part #25240AA060 first. It cost me over a hundred at the dealers but I used their part number and checked the internet. $18 and some cents! The solenoid at the same locale in the engine is not to be confused with this; this one is a pressure switch. You are hnto risking much $$ and it works for code Po 39, I think it is. There are two of these switches, one for each side of the motor. The one right next to the oil filler tube is the most likely. wilder

An errant VVT pressure switch will NOT throw a code...only a disconnected or bad actual solenoid will (PO026 and 28). Don't get them confused. Bad solenoids are MUCH more rare than cracked and leaky cheap pressure switches, btw. Getting a scanner proves much more useful for other more common codes...esp the dreaded PO420 as well O2 sensor codes et al later on.