P0400 Exhaust Gas Recirculation Flow Malfunction

[F1ferrari]

so i obviously have this code but i'm not sure what to do b/c i can't find any diags on this code.....has anyone had this code before and if so how did you fix it? (clean the egr tube,clean egr valve, replace egr valve and gasket???) Your help is greatly appreciated!

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[Gramma_Benz]

Found this:


You can clean the EGRvalve with some spray egr cleaner or a very good carbon cleaner i have found is to use the can of CRC brand maf cleaner with the spray tube.When you disconnect the lines you can also shoot the spray tube into the tubes to clean them out.

Or this:

Ah, the Engine Gas Recirculation System
I am looking at my haynes manual right now, and it's looks like a royal pain in the ***. let me write some of this in for you, to give you an idea of the different possibilities of your problem

"The EGR system is used to lower NOx (oxides of nitrogen) emission levels caused by high combustion temperatures. The EGR recirculates a small amount of exhaust gases into the intake manifold. The additional mixture lowers the temperature of combustion thereby reducing the formation of NOx compounds."

-EGR recirculates exhaust gasses to the intake.-

"The EGR systems are equipped with an EGR valve and also an "EGR and canister control solenoid valve" which recieves ported and manifold vacuum. The operation of the system is controlled by the ECM which operates the control solenoid valve. The manifold vacuun system utilizes a vacuum tap in the air intake system positioned after the throttle valve. The ported vacuum control system uses a vacuum tap in the throttle body which is exposed to an increasing percentage of manifold vacuum as the throttle valve is opened during acceleration."

-The EGR valve + Canister Control Solenoid valve work together to controll the flow of the exhaust gas into the intake. When the control solenoid valve is instructed to open by the ECM, this in turn opens the EGR, which then using vacumm, starts the system from the Canister to the intake. The more air that is sucked through the throttle body, the more exhaust gas is pulled from the system by vacuum.-

"A backpressure transducer (EGRC-BPT) valve monitors the exhaust backpressure as the engine RPM increases or decreses to aid in controlling the EGR vacuum signal. An EGR temperature sensor is also used to inform the ECM of the heat in the exhaust gas which is being supplied to the engine."

The EGRC-BPT simply makes sure that the exhaust backpressure doesn't overpower the intake vacuum. The temp sensor aids in the ECM's tuning of this function.-


If something in your system is clogged, it may be a vacuum line (which can be checked), or the actual exhaust return pipe (doubt that can be clogged).
Addition malfunctions can be attributed to the EGR valve + Canister Control Solenoid valve. If one of these solenoids were to fail, the system may either be stuck open, or stuck closed.


The haynes manual does give the instructions for how to
Replace the EGR valve unit.
Replace the EGR + canister control solenoid valve
Replace the EGR temperate sensor.

So it sounds like you may wanna try cleaning your EGR valve and checking all your vacuum hoses and go from there.

Good Luck!