Blinker problem on 2009 Jetta

I have a strange problem and would like some help on troubleshooting it. I know a few days ago all of my blinker lights were working properly since I had the car serviced at the dealer and they made me test all the lights before I dropped it off. But yesterday my “check the lights” yellow lightbulb indicator came on, so I thought, ok, probably one of lights burned out. But then, when I needed to turn left, I saw my blinker on the dashboard blink with twice the usual frequency, but the only turning light I could see from behind the wheel, on the left mirror was blinking normally. So, I stopped, got out of the car and looked around to find that neither of my front or rear left blinkers were working at all. So, here come the questions. How likely is it for BOTH lights to burn out at exactly same time? If they did, would this cause the dashboard blinker to blink at twice the usual rate? And if so, why is the mirror blinker blinks at normal rate? By the way, the right blinker is not affected by this strange affliction. Continuing, what is the best way to find out if this is (a) capacitor problem, (b) burned-out light(s) or ©(worst possible case)problem with a very expensive control board, which only can be fixed by replacing the board, which I am afraid to find out after taking it back to the dealer and first paying $100+ for diagnostics to then pay a lot more for repair.
Thanks in advance.


You are overanalyzing this, in my opinion.

Get a test light and make sure that LF and LR turn signals are getting power.
If they are, the test light will be blinking.
If the test light is blinking, replace the bulbs and go about your life.

The “dashboard blinker” is SUPPOSED to blink twice as fast to let you know you have a bulb out.

As the previous poster suggested simply replace the bulbs for a few bucks and continue on.