Skip the auto shop - Our mechanics make house calls

Q: SUV slowed from 60 to 40 mph and lost acceleration

asked by on

While driving over 60 mph on a busy highway, my SUV suddenly slowed to 40 mph and It thought it was going to stop. I pressed the gas pedal, but it did nothing. Then I tried to move to the right to avoid having an accident and while doing this, the SUV independently shifted and started accelerating again. After that I got off the highway and took back roads to get home. The next day I took the vehicle to the dealership and they could not find anything wrong with it. The engine light had been on for over a month, but even with that, they couldn’t locate the problem. They told me to come back if it happened again. One night I went to the store and on my way back to the house, the SUV completely stopped in the middle of the street, fortunately near the house. A neighbor helped me push it into the driveway. The next day it started and I took it to a different mechanic to have it looked at and the new mechanic told me the same thing: he would have to experience the problem before knowing what to do. I feel totally unsafe in this SUV. I don’t understand why the diagnostic tests don’t show anything. Can you give me any advise as to how to find the problem for this?

Diagnostic codes can be somewhat transient. If the engine management system observes the problem clearing after several drive cycles, it will turn off the Check Engine Light and clear the problem code. There is no "history file" kept. There are devices available to the dealer which they can temporarily install which can capture the state of the system when the driver presses a button for instance, allowing capture of temporary problems such as this. You can also purchase a device which plugs into the diagnostic port of your vehicle (On-Board Diagnostic II), which comes with an app which runs on your smartphone. This allows you to access the diagnostic codes immediately when the Check Engine light comes on, so that you can have a better idea of the problem.

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!

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: want change out of 3rd gear want go in reverse service light on.

Hello. I will be glad to help you with this. Shifting in an automatic transmission is controlled both electronically, via solenoid actuated valves for instance, and also by using hydraulic pressure to activate various pistons and clutches in the transmission....

Q: Hesitates when accelerating

Hello. This can be caused by the catalytic converter, but that is not too common with this symptom. If there is a hopping feeling, which is similar to a misfire, then most of the time this is caused by a...

Q: Car won't start, needs ignition switch replacement - 2002 Isuzu Axiom

Looking at the Isuzu repair documentation, I see no service bulletins that would indicate a programming update for an extended crank or no-start condition although there are software enhancements all of the time and not necessarily a bulletin-related to the...

Related articles

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 to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
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...