Skip the auto shop - Our mechanics make house calls

Q: Car independently downshifts on startup

asked by on

When I was slowing down, my car independently started downshifted very hard. I never shifted the transmission. This problem stopped happening for about a week and then started up again, This time the check engine light came on, but was not flashing. Now the problem is constant, both the hard downshifting and the check engine light stays on. I put it in neutral now when slowing down and this avoids more strain on the transmission. But when I shift into Drive, it hard shifts. Also, my car has a sealed trans fluid unit, so it’s probably not the fluid. I will be taking it to be serviced, but before doing so I want to find out what is wrong with it. What is your assessment of these problems?

There seems to be a problem inside the transmission and the code that has turned on the Check Engine Light may point to it. Other vehicles having similar symptoms have had faulty torque converter clutch solenoids or line pressure solenoids. I suggest hiring an experienced technician who can check the level and integrity of the transmission fluid and diagnose the trouble codes firsthand.

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 independently downshifts on startup

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: 2005 mini cooper s is parked and wont go into reverse gear. All of the other gears work except reverse.

Hello, thank you for writing in. The transmission may be having one of several issues. The shifter can become unaligned and need to be adjusted or replaced. The gearbox can also become damaged and misaligned, which also warrants them to...

Q: I need to fix my ac

The expansion valve is within the evaporator and the evaporator is under the dash. Considerable disassembly is required to access the valve. However, the valves don't go bad that often. It's a rather simple part mechanically speaking and so a...

Q: Just received car back from dealership ($698 tune up) car ceases in middle of street, smoke coming out,trans leaking , no fluid

It sounds like they used a transmission fluid exchange machine and they would have had to disconnect one of the transmission lines to perform the service. The dealer is responsible for any damage to the transmission. If you want to...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
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.