Skip the auto shop - Our mechanics make house calls

Q: Diagnostics show the EGR and idle air control valve - what does this mean?

asked by on

So I ran the diagnostics on my car and the code were the idle air control valve and the EGR CAME UP what will the best to replace them both

My car has 197000 miles.
My car has an automatic transmission.

The idle air control valve is a unit that monitors the air intake into the engine as it is mixed with fuel prior to entering the motor. When this is not working properly, this will cause an imbalance in the air/fuel mixture causing the car to idle rough or stall at low speeds. The EGR valve is a small component designed to allow the flow of exhaust gases into the intake manifold in controlled amounts. As such, it’s a simple valve that closes and opens as needed.

The EGR valve has one single job to do, regardless of the system configuration, type of control and number of sensors: that is, to either open and direct exhaust gases into the combustion chamber, or to close and keep them from entering. Whenever you start the engine, the valve comes alive and waits in a closed position, blocking the flow of exhaust gases. Once the engine reaches operating temperature and speed increases, the valve, either through vacuum or electronic control will gradually open, allowing burned exhaust gases to enter and combine with the air-fuel mixture inside the combustion chamber.

If you slow down sufficiently or come to a stop, the valve gradually closes and blocks the flow of exhaust gasses. After you shut off the engine, the EGR valve closes and remains in that position. When the EGR valve is clogged or dirty, as they are prone to, it may not function properly causing the engine idle rough, stall at idle speeds, cause the car to get poor fuel mileage, emit a strong smell of fuel due to excess hydrocarbons which also results in failing emissions tests. I would recommend having a professional, such as one from YourMechanic, come to your location to properly diagnose and repair the EGR valve.

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
  • Home
  • Questions
  • Diagnostics show the EGR and idle air control valve - what does this mean?

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: Traction light on

The TCL, or traction light, typically appears in conjunction with either the ABS, anti-lock braking system, light or with the Service Engine Soon Light. The traction control on your Mitsubishi Galant not only utilizes the ABS for proper function but...

Q: My car doesn't pass emissions because the catalyst system is below threshold, and the exhaust gas recirculalation is insufficient.

Hi there. The Engine Gas Recirculation (EGR) valve could be sticking or full of deposits from the exhaust system. Remove and clean the EGR valve before replacing it to see if the system will begin to operate. The oxygen sensors...

Q: 5 spd auto transmission problem

Hello there, the loss of the forward gears in your 2000 BMW 323i is caused by one of a few issues. The most common is low transmission fluid, shift solenoid fault, clogged transmission filter, torque converter, shift linkage or the...

Related articles

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...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
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.