P0400 is a diagnostic trouble code (DTC) because that "Exhaust Gas Recirculation flow Malfunction". This can take place for lot of reasons and also a mechanic demands to diagnose the certain cause because that this code to be motivated in your situation. Our certified cell phone mechanics can come to your home or office to carry out theCheck Engine irradiate diagnosticfor $114.99. Once we room able to diagnose the problem, you will certainly be detailed with one upfront quote for the encourage fix and receive $20.0 off as a credit towards the repair. Every our repairs are backed by our 12-month / 12,000-mile warranty.

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P0400 code definition

Exhaust Gas Recirculation circulation Malfunction

What the P0400 password means

P0400 is an OBD-II generic password that the engine regulate module (ECM) detected the engine exhaust gas recirculation (EGR) valve is no flowing recirculated exhaust gases when it is commanded to open the flow of gases right into the entry manifold.

What causes the P0400 code?

The EGR valve is no opening as result of no vacuum opening the valve indigenous the EGR manage solenoid or the EGR not holding vacuum.

The EGR temperature sensor is not registering a temperature readjust when the EGR valve is opened.

The EGR passages space blocked and will not permit flow of exhaust gases right into the entry manifold.

What are the symptom of the P0400 code?

The examine Engine Light will certainly be illuminated and also the password is collection in ECM memory.The engine can have one engine ignition ping or knock on acceleration.The engine will fail emissions from too much NOx in the exhaust tests.

How walk a mechanic diagnose the P0400 code?

Scans codes and also documents the freeze structure data in order to verify the problem.

Clears the engine and ETC codes and also road exam the vehicle to verify whether the password comes back.

Visually checks the vacuum hoses, wiring, and also connections to the EGR valve and control solenoid together with the EGR temperature sensor.

Disconnects and checks the EGR valve is getting vacuum come the valve once the regulate solenoid opens up on light to medium acceleration.

Checks because that EGR temperature sensor adjust and engine to bog down when the EGR is opened.

Removes EGR valve and temperature sensor to inspect for excessive carbon buildup or blockage the EGR tubes.

Common mistakes when diagnosing the P0400 code

Replacing the EGR valve prior to checking because that carbon develop up ~ above the EGR temperature sensor.

Replacing the EGR valve without checking the EGR pressure transducer for proper function.

How serious is the P0400 code?

A failure EGR valve can cause the engine come have excessive ignition that can cause internal engine damage to the piston and also valves.

The check Engine light on will reason the vehicle to fail emission testing from too much NOx gases.

What repairs have the right to fix the P0400 code?

Replacing the EGR valveReplacing a damaged vacuum heat to the EGR valveReplacing one EGR temperature sensor or cleaning the carbon turn off of the to fix itCleaning carbon the end of EGR tubes to intake manifold

Additional comments for consideration regarding the P0400 code

Code P0400 is triggered once the EGR temperature sensor go not watch a temperature change when the EGR is commanded come open. This sensors often tend to obtain a most carbon buildup that causes them to lose sensitivity to the warmth from the EGR gases.

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