Q: My car is having trouble turning over and when it does it can only go 20 mph max but I can't go uphill. What could be the issue?

asked by on August 02, 2017

Car won't go over 20 mph and is having trouble turning over. It also can't go uphill
My car has an automatic transmission.

It sounds like you may have a catalytic converter that may be clogged or failing. There are a number of reasons that may cause the catalytic converter to fail. They include: O2 sensor, fuel injectors, spark plugs, EGR valve system, exhausts manifolds, vacuum hoses, and MAF sensors. I would suggest having all of these components checked to be sure they are operating correctly. Generally, when the motor is continuously running too rich (too much fuel), this will ultimately destroy the internal components to the catalytic converter by way of igniting raw fuel inside the catalytic converter. Despite the catalytic converter’s ability to withstand very high temperatures, excessively rich fuel conditions can produce enough heat to push the converter material beyond it’s limits. These types of rich fuel conditions result in higher than normal temperatures that can cause matting erosion and burn away or melt converter coatings. If temperatures are high enough, the ceramic substrate itself will melt and clog. I would suggest having an expert from YourMechanic come to our location to inspect your vehicle.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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


Experienced Mechanic?

Earn up to $70/hr

What others are asking

How much to change an axle on a 2007 ford focus?

In order to get a proper quote for the needed repairs to fix the damage you will need to have the complete suspension checked to see all what got bent in the accident. You may need control arms, hub and...

Front passenger tire caved in.

Hello. If the front wheel caved in then it may be possible that the wheel bearing that was freshly installed may have come undone or let go. This can happen if the wheel bearing was not installed correctly. The same...

battery cable is too short to reach battery connection. Had to replace the connection because it broke off and now cable to short

You can purchase battery terminal ends with cables attached at most automotive part stores. You want to find the same gauge/thickness of wire or slightly larger. Then you'll need a lug or crimp fitting that matches the size of the...

No fuel pressure in my line. Car won't start. When it did star, it died and now won't start at all.

As you know, this may be a result of a faulty fuel pump. This may also be a result of a failing fuel pressure regulator as well. This is what monitors the fuel pressure in the system and maintains pressure...

Brakes are squeaking and brake light is coming on

This may suggest that your brake pads are worn and due to be replaced or that you have a leak somewhere in your brake hydraulic system. The brake reservoir has a sensor inside that detects when the brake fluid reaches...

Car makes horrible noise going over bumps

Hi. It could be the struts, but then again, it could be a lot of things. Some other usual suspects include the control arm bushings, link pins and ball joints. A trained mechanic will be able to listen to the...

2007 Honda Accord not going into gear

You seem to be having a hydraulic (fluid transfer) issue here. The leak may be in the slave cylinder, master cylinder or the lines and hoses that move the fluid from each part to the other. Look for leaks under...

The car makes ticking sounds while idling

The pinging sound can be caused by many different faults. Without more detail about the noise, I will take the best guess I can at this point. If the vehicle is pinging at idle there is a chance that...

Crankshaft broken

The crankshaft is a very important component in the motor and is balanced very precisely. If the crankshaft were to lose its balance for some reason, major engine damage would occur. This would also cause all of the main and...

Related articles

Symptoms of a Bad or Failing Throttle/Accelerator Pedal Position Sensor
Common signs of a faulty pedal position sensor include inconsistent engine response, reduced fuel efficiency, and the Check Engine Light coming on.
Jeep Certified Pre-Owned (CPO) Car Program
If If you are in the market for a used Jeep vehicle, you may want to check out cars under their certified pre-owned program. Many manufacturers have a certified pre-owned (CPO) program, and each one is set up differently. Read...
How Do Rain-Sensing Wipers Work?
Several Several decades ago, the only settings windshield wipers came with were low, high, and off. Later, an intermittent wiper feature was integrated into many windshield wiper switches, allowing drivers to reduce the frequency of wiper movements based on the...