Skip the auto shop - Our mechanics make house calls

Q: Car engine brakes on its own.

asked by on

When I'm accelerating and the car changes into second gear it'll downshift hard on its own and it makes a little whining noise. I know it's not the tranny. Could it be the MAF or IAC ?
My car has an automatic transmission.

What you are describing is often a sign of low transmission fluid or a faulty transmission control solenoid. As you know, automatic transmissions use pressurized hydraulic fluid to change gears. Every time a gear change is required, the car’s computer activates a transmission solenoid, which directs transmission fluid into the valve body to engage the correct gear. When this is faulty or not working properly, this can cause a delay in gear shifting or in some cases cause the car to not shift at all. This type of problem is amplified any time the transmission is low on fluid creating a drop in hydraulic pressure. I would recommend having a professional from YourMechanic come to your location to diagnose and inspect your vehicle.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. Car engine brakes on its own.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Air shock system not working

Replacing the air suspension in your Buick with normal shocks is a fairly straightforward process of repairing the suspension system with little headache. Enlisting the assistance of a certified mechanic, like one from YourMechanic, can make this process even easier....

Q: Tire is stuck on the truck, I can't change my tire because the tire won't come off

Hi, thanks for writing in. The rim has a centering part that will cause it to stick to the hub sometimes after being on the truck for a long time. You will need to remove lug nuts and after making...

Q: How to replace the cam shaft sensor.

The camshaft sensor on this engine is mounted on top of the synchronizer in the front center of motor. The noise may be in the housing and not the sensor. The sensor can be removed from the synchronizer housing and...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.