Skip the auto shop - Our mechanics make house calls

Q: My car will not idle at a stop light.

asked by on

my car shuts off sometimes but it will start back up but it would not hold an idle I have to hold down the Gas Pedal in order for it to catch idle
My car has an automatic transmission.

This may be a sign of a failing throttle position sensor or a failing or dirty idle air control valve. The throttle position sensor (TPS) is a sensor used to monitor the throttle position of the throttle plate inside the throttle body in relation to your foot position on the gas pedal. Based upon the inputs from the sensor reading your foot’s position on the pedal, the ECU then makes the direction to supply more or less fuel to the motor. When this sensor is not working properly, this can cause intermittent responses when pressing the gas pedal.

The idle air control valve reads the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at idle. This valve is controlled by the vehicle’s computer which will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed.

I would suggest having a professional from Your Mechanic come to your location to diagnose your idle air control valve and throttle position sensor.

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

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: Check Engine Light on again after thermostat replacement.

If the check engine light is coming on and a code like P1217 is in the computer then the computer is seeing an overheat conditions from the coolant sensor telling it your engine is overheating. This can be caused by...

Q: Service Engine Soon Light and P1441 Code, even after replacing purge solenoid

Although some codes require a certain number of drive cycles without problems to reset the Check Engine Light, it sounds like there is still fuel vapor flow from the EVAP system into the engine when there should not be. It's...

Q: Is there a tracking device on it

We can't be sure. I am sure most companies don't put tracking devices on their cars unless you have a package with OnStar or a low jack system but generally speaking most cars won't have tracking systems on them. If...

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...
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.