general problems of the 2012 Hyundai Sonata Hybrid

The contact owns a 2012 Hyundai Sonata Hybrid. The contact stated while driving 50 mph, the vehicle loss power and decelerated to 25 mph. The check engine warning light was illuminated. The vehicle was taken to the local dealer, but the vehicle was not diagnosed or repaired. The manufacturer was notified and the contact was referred to the local dealer for assistance. The failure mileage was unknown.

While driving the car will randomly rev very high it started about 3 weeka ago while driving at around an average of 45mph in city. It was initially just revving 3-4 times until I hit the break and it was isolated to one incident per drive. But last night after driving on I-25 at highway speed I turned to a slower busy street more stop and go traffic and the car started revving again only this time it did not stop after one incident. As soon as I hit the accelerator it went into a revving fit. And didnt stop I couldn't even drive it because I could not get it to accelerate. I tried turning off blue drive and tried shifting down to 1st gear so I could at least make it at 10-15mph but it revved up even in manual gear. I had to park it for the night in a pretty sketchy neighborhood and call an uber. The system didn't populate any codes and no service lights came on. Then, this morning when I went back to get the car to a mechanic and it was accelerating fine though it was sluggish. I managed to make it 2. 5 miles to a mechanic without incident but still no service engine light.

While trying to accelerate at freeway speeds (50-60mph), the "eco guage" revs up but the car will not accelerate - slows down in the middle of traffic. The oil pressure warning lamp flickers on and off as well. After the car is stopped and turned off, the car functions normally. Mechanics are unable to retrieve any codes from the system. The car has intermittantly dropped into this mode at least 10 times since we first experienced the problem in July 2018. The problem occurs at freeway speeds causing the car to rapidly decelerate in fast moving traffic with no advance warnings. This situation requires immediate evasive action to remove the car from high speed traffic lanes so it can be shut down and towed to the Hyundai dealer. My wife and I consider this a life-threatening situation as it has occurred in places such as the bay bridge (with no shoulder) and a lengthy underwater tunnel (again with no shoulder). We have taken it to the Hyundai dealer service shop four times. They have replicated the problem and have tried various repairs - replace transmission oil pump, replace inhibitor switch, install new auxilliary battery, and - finally - replacing the transmission. Even after the transmission replacement, the car shut down while the mechanic was test driving it and provided a code to replace the crankshaft position sensor. The mechanics still are not certain they have fixed the problem. It appears as if Hyundai is aware of the problem as their technical support staff have a protocol for repairing the car. Given the intermittant nature of the problem, the fact that it occurs at high speeds, and the potential danger of having your car rapidly decelerate on busy freeways, I think this is a safety issue that needs to be addressed by Hyundai. Attached is the original service record that describes the problem (date 8/6/18). The most recent occurrence was 11/27/18.

This problem has been getting progressively worse during the last 6 months. While driving or stopped at a light, the vehicle has sudden unexplained acceleration. The acceleration happens with or without the foot on the gas. When in drive, the driver can remove his foot from the gas and the vehicle continues to accelerate and pick up speed. The condition is extremely hazardous and warrants further investigation.

When accelerating from a stop, the vehicle takes excessively long time to go from 0-25 mph, so much so , that when merging into traffic it has unpredictable acceleration. At various times I would step on the gas pedal and sometimes it would have a 3-5 second delay before going forward. When it finally accelerates sometimes it has a popping sound and often the car lurches. I have brought it in 3 times for Hyundai to find the problem but each and every time they have said they were not able to find anything wrong with the car.