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: Door not opening from inside

If the door will still open normally from the outside, I would normally suspect that one of the plastic clips that hold the linkage for the door handle has broken. Have a certified mechanic come and take a look at...

Q: Steering wheel locks and hard to maneuver my vehicle off the road.

Hi there. The steering wheel lock solenoid could have lost power intermittently causing the lock to engage when the key is in the ignition switch. The solenoid could be damaged and needs replaced in the steering column. I recommend seeking...

Q: Emission control leak.

This code may be caused by the canister purge solenoid is leaking or you did not tighten the gas cap. Either way the leak should be cleared first and do a physical inspection of the fuel system. Then to check...

Related articles

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...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.
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.