Skip the auto shop - Our mechanics make house calls

Q: Check Engine light, code P0404.

asked by on

The Check Engine light on my car is coming on. I get a code P0404, EGR insufficient flow.

A: Having the engine code is a great first ste...

Having the engine code is a great first step to getting your Pontiac Montana running up to speed again. This engine code is reading EGR, which stands for Exhaust Gas Recirculation. The EGR’s job is to redirect a measured portion the exhaust gases back into the engine. Once back inside of the engine, the now inactive exhaust gas displaces portions of both the oxygen and the fuel located in the cylinders. This will lower cylinder temperatures, which in turn lowers NOx (oxides of nitrogen) emissions. The computer in your Pontiac carefully meters the amount of exhaust gases that are recirculated. This keeps the vehicle’s pollutant emissions lower while additionally not changing the engine’s peak performance. When the amount of exhaust gas entering the cylinder gets too high the engine will not idle, causing it to stall. This is the reading of the check engine light you are experiencing.

The EGR repairs can be as simple as removing the EGR valve, thoroughly cleaning out the EGR port and reinstalling the EGR valve to correct the code issue. However, because this repair is connected to emission issues, it is best to have this issue inspected by a certified mechanic so all safety precautions can be met.

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: Car stalling and then accelerating while driving

Many issues can cause a stalling concern while driving. Ensuring that all of your fluids are at the right fluid level is very important. An inspection should be carried out to make sure that there aren't any fluids leaking from...

Q: Whining after new installation of power steering pump

You either have excessive air in the fluid of the system that will gradually work its way out over a few days to a week, or the pump is defective. Try not to hold the steering in a locked position...

Q: My engine light is on and after turning on my and driving for 5-10 minutes my VSA and "!" In a triangle comes on

Hi there. Best practices automotive diagnosis for today's cars, trucks and SUV's begins by completing a diagnostic scan to determine if any error codes have been detected and stored in the ECU. Since you seem to have a warning light...

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...
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 P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...