My friend's 2015 Hyundai Sonata (2.4 GDI engine) was idling in the parking lot, and the (student) driver accidentally floored the accelerator (while the vehicle was in park).

Shortly thereafter (though I don't know exactly how long, probably around a minute), the engine died and cannot be restarted.

The battery is fully charged, and my friend had AAA try jumpstarting it anyway in case the battery was too weak, with no result.

When the key is turned to the Start position, all the lights and electronics shut off (as I believe they are supposed to do), and we can hear the starter engage. Watching the belts, it looks like the engine turns 1-2 degrees, then stops.

I checked with a scan tool and the only code I found was a pending P2122 (low voltage in the throttle position sensor), which I assume was only because the engine was not running.

Thinking their might be some physical damage to the engine, I asked her what it sounded like when it shut off (if there was a bang, pop, or other loud noise), and she said that it shut off so quietly that she didn't initially realize it had turned off.

What could be wrong with this car? What should I have my friend try next?

2 Answers 2


The P2122 message is not a red herring, the throttle position sensor should be working even with the engine off, and if it isn't being read that is likely why the engine won't start. Revving at idle shouldn't have caused it to fail, you should be able to stamp on it as much as you want without problems, it's either a coincidence or it triggered an impending failure.

The P2122 will be one of these:

  1. Wiring fault: the wiring or connections going to the throttle sensor could have a problem, or the connector may have come loose. Check the harness for breaks or frayed wiring
  2. Sensor failure: stuff breaks, and it could just be the sensor has a straightforward failure, in which case it needs to be replaced
  3. The ECU may have failed: this is the computer that manages the engine, however this is pretty unlikely as you'd probably be seeing other codes as well. It's most likely 1 or 2.

My friend had the car towed to a mechanic, who told her that the engine is seized and will either need to be replaced or the car junked. The mechanic said this is completely unrelated to anything her teenager was doing, it just happened to happen exactly then. I told her to look into whether she is included in the Hyundai class action warranty extension which would have Hyundai replace the engine.

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