Q: Car struggles to go up hills and only goes 40-60 mph depending how steep the hill is. What's wrong with my car?

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Whenever I go up a hill my speed quickly drops from around 65/70 mph to 40-55mph depending how steep the hill is. And if I try to accelerate more the car won't let me. It just remains at the same low speed. Once I am out of the hill and enter a flat road the speed goes back up to 65/70mph. Also, my check engine soon light has been on for a few years now, but mechanics I've taken it too can't seem to figure out why it is on. They just say it's a sensor but don't know which one. Despite the light being on the car has been running fine except going hills. In addition to going hills, it sometimes struggles to pick up speed quickly when entering a freeway. What could be wrong with my car or this behavior normal for this kind of car and it's age?

My car has 47000 miles.
My car has an automatic transmission.

Hi there:

Anytime a check engine light is illuminated it’s because a sensor has detected a mechanical or electrical fault that impacts the vehicle’s performance. If the mechanic you go to hasn’t completed a check engine light inspection; which means they actually download these error codes; then you should find a different mechanic who knows how to complete this basic diagnostic step. In order to effectively diagnose the source of your Nissan’s acceleration issues, you might want to have one of our mobile mechanics complete a car is slow to accelerate inspection; which will allow them to download those error codes first and determine why your Nissan is sluggish on hills.

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