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: Why wont my hybrid start

This could be any number of things ranging from a faulty starter relay to potentially a problem with the charging system such as a faulty alternator. If the starting is intermittent and does not require the car to be jumped...

Q: Q: Should I change my rotors?

If your rotors do not have a good clean smooth surface for the new pads to ride on then the pads will not be able to seat properly. This can lead to vehicle pull to one side or lack of...

Q: Malfunction indicator lamp is on!

Code P2647 stands for Rocker Arm Oil Pressure Switch Circuit High Voltage. This switch is part of the the variable valve timing (VETC) system. The powertrain control module (PCM) activates an oil control solenoid to charge/discharge the hydraulic circuit of...

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...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...