Scotty, 

I drive a 2010 Mazda3 that has around 102,000 miles on it. I bought it new, and do my best to maintain it (as I do all my vehicles) and it has served me well thus far, with a few exceptions. In the past, I've had to have the entire ABS hydraulic unit replaced, as well as a bunch of lines and wiring harnesses for the engine. Both of those issues happened in a 3-month period and totaled around $5000. And that was two years and 20,000 miles ago. I'm in the military, and also had to leave it sitting for 9+ months while I deployed right after those repairs (I replaced the battery when I got back last year and it started right up without issue). Been driving fine since then, until the check engine light came on last week. Took it to a local mechanic I trust, and he cleared out the code to see if it was just a one-time blip. Drove it for twenty miles, and the the light came back on. The code is P2004 "Variable Tumble Shutter Valve Stuck Open (Failure Type 00)".

What does this actually mean, and what will it take to get it fixed? Am I good to just keep driving the car like this, or am I doing damage to the engine? I really don't want to dump another massive amount of money into this car. Should I just go ahead and trade it in for another one, or is this something that can be fixed quickly/cheaply? I'd appreciate any advice/wisdom you can give. Thanks.

TL;DR

Make/Model: Mazda3 I 4-door Touring

Year: 2010

Engine: 2.0L DOHC 16-valve VVT I4

Transmission: 5-Speed Sport Automatic

Mileage: ~102000

Code: P2004

Code Description: Variable Tumble Shutter Valve Stuck Open (Failure Type 00)