What do you think happened? Jetta won't start and then easily jumpstarted

General Discussion
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Hello! I hope the community can help me figure out what’s going on. My 2016 Jetta (44K miles) did not start today. It was doing totally fine yesterday and today just nothing. It is the push button Start, so I thought it was the battery in the FOB. But I did not change the battery right away as I still tried to start it by holding the key close to where a normal key would go (it worked before when the FOB battery died.) Nothing worked, so I called the tow truck. The tow truck guy said he could jump start it for me and the car started! There were no signs on the dashboard indicating that something was wrong with the battery. Since it was easily jump started, could it be that while I was futzing around with the dead key the battery got affected?

The big question is, with no lights on the dashboard showing that anything is wrong, should I take it for diagnostics to the dealership? They’d charge me $150 for it.

Thank you!
Alla Kamins

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After 5 years, it is entirely possible that the car’s battery (not the fob battery) is depleted.
Go to an auto parts store for a free load test on the battery, and–more than likely–the meter will read “fail”.

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If the car battery is as old as the car (5 years) you likely need a new one. If the dealer wants $150 to diagnose a dead battery, tell them to pound sand and drive to advance auto or autozone, where they will test your battery for free.

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Thank you! And the dashboard would not show me if the battery is dying? I was hoping my new-ish car would tell me things like this?

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No, it won’t just tell you it needs a new battery.

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Note: I presume by “won’t start” you mean it doesn’t crank the engine; i.e. you don’t hear that rrr rrr rrr sound like you normally do.

It would indeed be theoretically possible for the car’s designers to have provided a battery test function. There’s a few reasons why I expect they didn’t.

  • Cost , both for the engineering development, and the per/car electronics cost
  • Reliability , the battery test function could fail, making the owner think there’s a battery problem when there isn’t.
  • Problematic batteries usually provide some warning before they fail completely. Slow cranking, that rrr rrr rrr sound, clicking, etc. So the owner usually has time to correct the situation before the car won’t crank and start up at all.

If you know how to work a DVM, here’s how I do a basic test of the battery and charging system:

Before the first start of the day the battery should measure about 12.6 volts; immediately after starting the engine, 13.5 to 15.5 volts.

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DVM-Digital Volt Meter In case you did not know. and if not you probably wont know how to use one.

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Not really . It is quite common for a vehicle battery to work several times during the day and then just not work at all with no warning signs.

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Nope. A dedicated (and somewhat sophisticated) battery tester gets attached to the battery for the test.

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Thank you, all! Went to Autozone and the test showed the battery was dead. Now have a good new battery:) The silly airbag light came on though through all this ordeal and I guess the airbag light died…

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+1
I vividly recall driving home from work, running several errands in the car, and then a couple hours later–just when I was supposed to go back to work for an evening meeting–the battery was dead.