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

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: When at idle truck wants to stall

Hello there, many common faults will cause your 1986 Dodge W250 to want to stall when coming to a stop and sputter under acceleration. The most common causes are the power brake booster, vacuum leak, MAF sensor, oxygen sensor, crankshaft...

Q: BMW e90 320d jerking at pull away, and in 2nd gear, reduced power, turbo sound has changed.

Hi there. Since this occurred right after driving in some dusty conditions, I would check the air filter first. If the air filter is dirty then this will occur. If the air filter is fine, then I would also clean...

Q: Brake squeaking

Hi there. More often than not, the squeaky noise on front brakes is causes by metal to metal grinding, as there is typically a small metal groove that let's owners know that the brake pads needs to be replaced. However,...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
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.