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MIL, ESC, Brake, and "Auto Hold" Lights Turn Yellow and Loss of Engine Power

This morning around 10:30AM, driving at over 70 mph to San Francisco in the rain with 4 passengers for a business meeting, my 2017 Sonata PHEV shudders as if the tires slipped and spun on the wet pavement. I noticed that the ESC light was yellow and also a little while later, the Brake light and "Auto Hold" lights turned yellow. I thought I had accidentally hit the Auto Hold button and had to wait for an opportunity to press it while pressing the break to eliminate the light. When the opportunity came, I could not get the light to go off. Also, tried turning ESC off and on again but the light stayed on.

Parked the car in the garage, went to the meeting and came back at 3PM, and started back the drive home with my passengers. All the above lights were on. About 30 minutes later, in the 6 lane I280, all of a sudden the engine power drastically reduces abruptly and the car starts to slow down. With great difficulty in the evening rush hour commute traffic, I managed to shift lanes and take the next exit and went into a parking lot and stopped the car. After a few minutes, start it back up and now the MIL comes on along with a message to take the car to the dealer. Ran the Vehicle Diagnostics and get the message of possible condition with the ECS. Start driving the car with the same lack of engine power. Drove through local road and reached home after 4 hours for what should have been a 1 1/2 hour trip. On the way back, called Bluelink and they confirmed the need to take the car to the dealer and made an appointment for me for tomorrow.

I wanted to take a picture of all the lights, so around 10PM I started the car, and all the lights are GONE except MIL. Decided to test drive the car and found no loss of power. Took it to the nearby freeway and floored it with full power response!

Has anyone else seen such behavior? I will update tomorrow what the dealer will report, but I am afraid they are going to just reset the MIL and suggest that I was hallucinating.
 

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Discussion Starter #5
Here is the write up from the dealer:

"Duplicated engine light is ON, scanned for codes and P033500 Crankshaft position A circuit P0A0F Engine failed to start C164808 CAN signal error HMS ACC SCC CL35808 HCU Torque control unavailable for SCC C13 6081. Cleared codes and then test drive vehicle. Only code that came back was P033500 Crankshaft position sensor A circuit active. Checked harness OK. Pulled sensor and is dirty, but when performing active monitoring on tablet would not show it cranking on or signal. Recommend replacing crankshaft position sensor and check. Replaced crankshaft sensor and test drive vehicle. No lights came back on. Recheck for codes. All clear. Operates as designed at this time."

Any way, got the car back today and I hope this really was the root cause. I have a hard time though seeing the sequence of symptoms that I saw are explained by this as the root cause.
 

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Thanks for these details and please let us know how this repair turns out for you. This type of problem can cause all sorts of other issues and codes as well. Based on how the vehicle was driving and such it tends to make sense.
 

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MIL, ESC, Brake, and "Auto Hold" Lights Turn Yellow and Loss of Engine Power

This morning around 10:30AM, driving at over 70 mph to San Francisco in the rain with 4 passengers for a business meeting, my 2017 Sonata PHEV shudders as if the tires slipped and spun on the wet pavement. I noticed that the ESC light was yellow and also a little while later, the Brake light and "Auto Hold" lights turned yellow. I thought I had accidentally hit the Auto Hold button and had to wait for an opportunity to press it while pressing the break to eliminate the light. When the opportunity came, I could not get the light to go off. Also, tried turning ESC off and on again but the light stayed on.

Parked the car in the garage, went to the meeting and came back at 3PM, and started back the drive home with my passengers. All the above lights were on. About 30 minutes later, in the 6 lane I280, all of a sudden the engine power drastically reduces abruptly and the car starts to slow down. With great difficulty in the evening rush hour commute traffic, I managed to shift lanes and take the next exit and went into a parking lot and stopped the car. After a few minutes, start it back up and now the MIL comes on along with a message to take the car to the dealer. Ran the Vehicle Diagnostics and get the message of possible condition with the ECS. Start driving the car with the same lack of engine power. Drove through local road and reached home after 4 hours for what should have been a 1 1/2 hour trip. On the way back, called Bluelink and they confirmed the need to take the car to the dealer and made an appointment for me for tomorrow.

I wanted to take a picture of all the lights, so around 10PM I started the car, and all the lights are GONE except MIL. Decided to test drive the car and found no loss of power. Took it to the nearby freeway and floored it with full power response!

Has anyone else seen such behavior? I will update tomorrow what the dealer will report, but I am afraid they are going to just reset the MIL and suggest that I was hallucinating.
 

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Same issue here on my 2018 sonata as I was driving down interstate and my cruise control just shut off and lights came on for auto hold in yellow; quick fix if you are traveling in the middle of nowhere on a holiday weekend like me today...stop car, press brake pedal while doing this, turn parking brake on, turn parking brake off, turn car off and re-start. This should reset your system and let you now use your cruise control. I figured this out after quite a while on side of road and lots of bad words. I hope this helps someone out till you can get your car in for service.
 

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2017 Sonata Hybrid SE

Same exact issue as you except only the check engine light comes off and on during the loss of power.

Faulty pressure sensor replaced 3 times already. Last one was at a different dealership too. Issue pops back up after a few months. I'm staying far away from any Hyundai vehicles after this.
 
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