I have a few problems with my Elentra Automatic Transmission 1.6 2004 vehicle, and I don't know if these problems are due to the same part. My problems are:

1. The car behaves like 3rd gear all the time. As a result, the engine is very difficult to take off, especially on the slopes.
2. When I turn on the air conditioner in the car, the car shakes. I feel like it will stall at any moment.
3. When I manually take the car to L, the car pretends to be in the park gear and doesn't move. When I manually take it to 2, it moves. But it takes off hard.

The car was doing these problems 7-8 months ago, but when I stopped and started it, it runs normally. I took it to a mechanic. He said there might be a problem in the TCM. He looked for transmission issues by plugging in the wires. He said there was no problem on the screen. Afterward, I did not encounter the same problems for a long time. Recently I went to a place with plenty of slopes, the car shifts a lot. I parked in an uphill place. I left the load on the park gear, not on the handbrake. With a little difficulty, I could change gear and take off. Later, these problems started to occur again. The problem went after a day or two. Yesterday, when I passed the roads with plenty of slopes, the car lately shifts from 2nd gear to 3 and the same problems arose. This time the problems did not go when I rerun the car. Problems continue now. Yesterday, I changed and renewed the transmission oil completely to make sure there was no oil-related problem.

What are your suggestions and solutions? Do you have any of the same problems?
Thanks.

 

When the electronics of the system detect a problem,it places the system in"Limp Mode", which is third gear. That is to get the operator off the road and to a service facility.

The system will reset when the key is turned off, but will return to limp mode as soon as the problem is detected again.

There are many things that can cause this and a capable scan tool is required to get this info.from the system.

 

I checked with an obd. Problems are those:

P0134: Oxygen sensor circuit (Bank 1, Sensor 1)
P0031: HO2S heater control circuit low (Bank 1, Sensor 1)
P0325: Knock sensor 1 circuit Bank 1 or single sensor

Could you estimate the problem better now?

 

Before replacing anything, I would check all the fuses.

Then if all is well, find out what is happening with the oxygen sensor heater voltage at the sensor, if it is present or not, . If it is , then consider replacing the sensor. If you just replace the sensor and there is still a voltage problem, you just replaced a good part and that is not what we should be doing.

Because there are , so far , 2 related systems with a problem, look for what supplies them with the operating power to function.

We always check for power and grounds before condemning any component. As you can see this requires some special equipment and I'm not sure you have it available at this time.