gas cap problem causing warning lights/performance issues?

[2012GT]

Oddly enough (from my username), I have a 2012 Legacy GT with the 2.5L turbo/6-speed stick, that's recently begun exhibiting dash warning lights (Cruise and Brakes lights flash, Traction control and Check Engine lights steady on), in addition to a rough idle and rough engine performance (chugging when under quick acceleration, etc.). The car only has 74K miles on it and has been studiously maintained/cared for.

I've seen Google reports (many, actually) of this being caused by a loose and/or defective gas cap. I've checked the cap and it isn't loose, but it could be worn/defective after 10 years of living by the Jersey shore.

So, I'd be grateful if anyone can provide any insight, if you've experienced a similar problem.

Thanks,
Pete

 

[Ecmbuster]

A loose gas cap will never express the problems you're having. A non venting fuel cap will however and is quite rare.
Rough running or misfiring will not be "gas cap related".
Rough running includes: ignition coils, spark plugs, fuel starvation, variable valve timing issues MAF defects and or poor fuel quality.
You need to access fault codes in all the controllers, especially in the ECM.
FreeSSM for a PC is a good choice and only a cable is required. Works with Windows 7 and Windows 10
JDMscan and ActiveOBD also works well with Android.

FreeSSM Link:
https://sourceforge.net/projects/freessm.berlios/files/latest/download
Cables:
VAG-K + CAN USB
OR
(FTDI) FT232BL USB

Android Tools Used:
JDMscan Application
Cables:
VAG-K + CAN USB
OR
(FTDI) FT232BL USB
with OTG cable if Android supported

ActiveOBD Application
Bluetooth OBDLink MX +

OBD II tools will also help and the best BlueTooth device is the OBDLink MX + or BAFX ELM 327 is also recommended for general use.
Access to recorded faults is the first step and guide.