I have got a few issues with my POLO TDI 2012. My car starts and runs, one day when I start it in the morning, car idles roughly (rpm jumps up and down quickly). Then the car starts acting weird, like the head unit goes off for no reason, headlight dims sometime(especially when reversing). The main problem is I found there is a big time gap between changing gears, I assume it's a gearbox issues but the problem sometimes goes away, and when I go uphill the car refuse to change gear, I have to push on throttle more, but it goes to limp mode after changing gear. I took it to mechanic they can't find the problem. OBD sensor reads turbo underboost code.
Here is what they have checked:
- Smoke tests there is no vacuum leak in the system
- EGR checked not clogged
- Fuel filter
I just found my battery indicator shows red, but I asked a few friends they all said those problems don't sound like a battery issue.
Can it be the battery? or what else it could be.