Q: My car won't go past 20mph. I've gotten the codes, battery, alternator check. But after jump starting battery everything is fine.

asked by on

After a long day of driving throughout the city my car didn't want to start. So I tried starting it again and it did. But I couldn't go past 20mph. I let my car sit in a parking lot for at least 30 minutes then drove it home. It still wouldn't go past 20 mph. After making home. My brother mentioned maybe it's the battery so two hours later he came by and jumpstarted my battery. I drove it around the block afterwards and everything was fine. The next day I took it to O'reily auto parts to get the codes ran on it and everything was fine except for my emissions valve. My alternator was good and my battery was good as well but needed to be charged. Could my battery be the issue or maybe a sensor or something else?

My car has 120000 miles.
My car has an automatic transmission.

Hi there. The job of the battery is to provide electrical power to start the engine or power accessories when the vehicle is not running. When the vehicle is running, the alternator takes over the job of supplying power. Due to this fact, I doubt that the battery is the cause of the lack of acceleration problems you are having. I would suspect that this is caused either by a sensor that is faulty, or an ignition / fuel system component that is dirty, has a bad electrical connection or is damaged and requires replacement. It’s probably best to have a professional mechanic come to your location to complete a car is slow to accelerate inspection to determine the source of this problem.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. My car won't go past 20mph. I've gotten the codes, battery, alternator check. But after jump starting battery everything is fine.

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: High fuel consumption

There are a number of things that can cause poor fuel mileage. A faulty camshaft position sensor is one of them. The camshaft position sensor is a magnetic sensor that monitors camshaft speed to regulate ignition timing and fuel injection...

Q: Honda Civic blowing cold air at idle and making noise when braking

Claimed by Mia Bevacqua

Q: What is the proper tire inflation?

It’s vital that your tires have the right amount of air in them. Too little (under inflation), and they’ll wear on the edges. Too much (over inflation), and they’ll wear down the center. Neither is a good situation to have....

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
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...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...