Skip the auto shop - Our mechanics make house calls

Q: Reduced engine performance that smooths out after 40 MPH until acceleration.

asked by on

Vehicle runs roughly and has a read out thats says reduced engine performance. Initailly, the vehicle runs rough at 40 mph, then smooths out until I try to accelerate.

A: Hello, being that the engine and transmissi...

Hello, being that the engine and transmission are computer controlled, a scanner needs to be connected to retrieve codes. If there are no codes present the technician will be able look at data retrieved by the scanner and come to a possible solution. When symptoms like this occur with the "reduced engine performance" message, the vehicle is going into limp home mode trying to protect the engine and or transmission from further damage. You should enlist the aid of a mechanic to inspect your engine.

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・Save up to 30%

Get a quote

What others are asking

Q: What type of oil is best for this car if I need to change oil? I have a 5 cylinder straight 2006 Xc90.

The use of the wrong type of oil can sometimes cause codes like these, but this is rare. There my be a malfunctioning variable valve solenoid on the vehicle which can be the solenoid itself, actuator on the camshaft or...

Q: Dome light and trunk light not working all fuses are good

The lights are controlled by the body control module through the auto shutdown relay in the right instrument panel fuse box. Either the body control module is not activating the auto shutdown relay or the relay is bad and not...

Q: Sudden Coolant Leak

The radiator tank is cracked and the radiator needs to be replaced. Replace the upper and lower radiator hose and the thermostat at the same time. They will save you more work in the near future. If you need to...

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...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.