Suddenly the RPMs shot up and the vehicle would barely go faster than 20 MPH?

AMISFITLIFE

MEMBER
2016 KIA FORTE
AUTOMATIC
164,000 MILES

Two months ago, I pulled onto the street and within a minute the RPMs shot up and I could barely go 20 MPH. Since then, I had several Instances of the same thing, but they were briefer. If I kill the engine and restart the issue disappears and the car drives as if nothing happened.
I have no check engine light. The battery and alternator test fine. There is no stalling or sputtering. I have no leaks anywhere and no trouble shifting gears. The mechanic who looked at it said he felt it was most likely a transmission problem. The car pulled no Transmisson codes.
It did pull an airbag code as well as the history codes.
C1109 voltage low
C1622 EMS invalid vehicle speed.
B1112 ignition voltage low.
I'm stumped and don't know what to do next.

3 Replies

JACOBANDNICKOLAS

MECHANIC
108,230 POSTS

Hi,

The codes can be related to the transmission. For example, the C1622 is related to a faulty speed sensor and the power steering assist.

Based on your description, it sounds like the transmission is slipping. This can be caused by a few different things. For example, low transmission fluid, low line pressure, work clutch plates, and so on.

If you haven't already, check to see if the fluid is clean, full, and doesn't have a burnt smell to it.

Let me know if you have a 1.8L or a 2.0L engine so I know what transmission to look at.

Take care,

Joe

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Friday, October 20th, 2023 AT 3:40 PM

AMISFITLIFE

MEMBER
3 POSTS

It's a 2.0. If it is a slipping transmissonis their anything that would fix the issue short of a complete overhaul?

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Monday, October 23rd, 2023 AT 11:10 AM

JACOBANDNICKOLAS

MECHANIC
108,230 POSTS

Hi,

If it is slipping this bad, I don't feel an additive would help. However, a transmission just starts slipping this badly all at once. Also, it would have set codes related to the transmission. I feel it is a voltage-related issue.

I attached the diagnostics below related to the C1109. Take a look through the diagnostics and let me know if you are comfortable performing this. Also, let me know if you have checked the transmission fluid's condition and level.

Take care,

Joe

See pics below.

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