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Pete, Oldsmobile Technician
Category: Oldsmobile
Satisfied Customers: 27918
Experience:  17 years Oldsmobile training and experience.
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Olds alero: shifting hard..gear and first gear..driving home

Customer Question

My 04 olds alero is shifting hard into gear and first gear while driving. happened before and was brought to a shop and they said nothing was wrong and it simply stopped doing it. I was driving home yesterday and at random it has happened again. my car has been maintenenced very well, including tranny flushes accordingly. any advice as to what might be wrong? Could it be a tranny sensor?
Submitted: 6 years ago.
Category: Oldsmobile
Expert:  Pete replied 6 years ago.
Hello and Welcome to Just Answer.


There are some common components that can cause a hard shift like this.

First is the pressure regulator electrical solenoid inside the transmission.This solenoid can stick and create high pressure in return can cause a hard shift from park to drive,etc. or hard shifts when driving when the transmission up shifts.

This is one of the more common components to fail and cause this type of problem here as I have had to repl;ace quite a few of these before.

The other component is a fault with the mechanical portion of the transmission valve body.The valves can bind or stick in the valve body which can cause this problem as well as debris build up in the valve body.In some cases just having the transmission flushed will free up and remove some of this debris and may correct this problem.In other cases the valve body would have to be removed and inspected to see what is at fault then determined if it can be repaired or if the entire valve body needs replaced.

The best way to have this diagnosed as to what component is at fault is to have a transmission shop or dealer test the system when it acts up.If they check/test it when it is shifting properly then the tests would show everything is o.k.

It is usually the higher mileage vehicles I see issues with the valve bodies being at fault usually above 50,000 miles.Below this is most common for the pressure control solenoid but in this case it could be either or causing this problem.

If it is the solenoid this can cost up around $100 for the part and around 8 hours labor to have it replaced.

If the transmission needs a new valve body or the valve body repaired this can cost up around 9 hours labor and depending on what needs to be done maybe $200 for parts or if the valve body needs replaced it can cost up to $1000 for the new valve body.

The best thing to do is to have a shop keep a hold of the vehicle and drive it periodically so they can test it when it acts up to locate the problem and then it can be repaired from there.

Let me know if you need anything else,click accept if you feel satisfied with your answer as this is how I get credited for my time,Thanks Pete!
Customer: replied 6 years ago.
What about an IAT sensor? I have been looking on other forums and I've seen a lot about IAT sensors and vacuums
Expert:  Pete replied 6 years ago.
If the IAT sensor was faulty then the check engine light would come on and there would be a code set that is related to the IAT sensor.

The most common problems for this concern are listed above with either the valve body or the pressure control solenoid.

Thanks Pete!