Skip the auto shop - Our mechanics make house calls

Q: Erratic idle - 2013 BMW 335i xDrive

asked by on

Recently, I had my serpentine belt replaced. Since then I have had occasional idling issues. For example, sitting at a traffic light I notice that the idle can drop down to 500 rpm and then revs up to 1200 rpm.

My car has 30000 miles.
My car has a manual transmission.

This is a common sign of a dirty or failing idle air control valve. This is a unit that monitors the air intake as it is mixed with fuel prior to being injected into the motor at low speeds or at idle. This unit also assists with the deceleration process as you let off the gas pedal bringing the engine back down to an idle. When this is not working properly, you may experience an erratic idle as you describe.

I would recommend having an expert mechanic, such as one from YourMechanic, come to your location to determine why the idling is erratic and repair your idle air control valve if needed.

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: The car won't run for longer than 30 sec.

When the car will only run with the choke applied, this suggests there is a larger fuel delivery problem. Start by checking the fuel lines, filter, etc., to be sure they are all free of dirt or any kind...

Q: I have a 05' 330XI that will not move into gears. Tried putting it in neutral but still wont move.

The noise that you heard was from the transmission area. Check to see if the driveshaft has come apart or if the tail shaft has broken. If there is nothing wrong with the driveshaft or tail shaft, then the one...

Q: Coil replacement - 2010 BMW 335i

Unfortunately, there is not enough information here to properly diagnose as a rumbling sound coming from an engine (especially a high performance engine) is somewhat normal in many cases. The service engine light could be on for many reasons. I...

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...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...