EGR Flow

I have a P0400 error on my Ford Escape. I am attempting to remove the EGR valve. Due to its location, it is extremely difficult to access the nut on the EGR exhaust tube. I am pretty sure it is a 1 1/16 inch nut, but I have not figured out a way to adequately obtain enough leverage to get the nut off, give the limited space. Can anyone recommend a method of removing this nut on this particular make and model?

My car has 110000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
In order to get the nut loose you will have to use a crow foot with an extension and breaker bar to get it loose. The space is limited and this is the only way to break it loose.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

The EGR valve is located in the engine compartment (underneath the hood).
What the P0400 code means. P0400 is an OBD-II generic code that the engine control module (ECM) detected the engine exhaust gas recirculation (EGR) valve is not flowing recirculated exhaust gases when it is commanded to open the flow of gases into the intake manifold.
The EGR system is an emission control device designed to recirculate exhaust gas into the engines air intake system and back to the combustion chamber to control nitrogen oxides or NOx.
The Exhaust Gas Recirculation (EGR) system is a part of the vehicle emission control. It directs a portion of exhaust gases back into the engine intake to lower the combustion temperature, read more how the EGR system work. The code P0400 is set when the EGR system flow is less than expected.
Where are these sensors located? Mechanical EGR valve position sensors are mounted on the top of the EGR valve. EGR pressure sensors will be located close to the EGR valve as the exhaust gas hose must be connected to the sensor as well as the valve.
EGR flow rate can be inferred by the difference between the fresh airflow into the intake system and the charge flow from the intake system into cylinder.
Technically you can drive without a working EGR valve.

It won`t affect the health of your engine, but it will hurt the environment. The role of your EGR valve is to reduce the number of toxic NOx gases in the air, so if it isn`t working quite right, more toxic gases will be released into the air.

Removing the EGR valve is going to improve the efficiency and performance of your vehicle and it is going to be a lot more powerful. The EGR valve, while a well-intentioned design feature is impractical in the sense that it sacrifices the performance of the engine in order to ultimately work against its own goal.
What does the P0401 OBD-II diagnostic code mean? Also known as insufficient EGR flow, this particular OBD-II trouble code indicates the engine control module (ECM) has detected the exhaust gas recirculation (EGR) valve is not allowing sufficient flow of recirculated exhaust gases into the engine.
Low pressure EGR, also known as long route EGR, consists of taking part of the exhaust gases from the DPF outlet and introducing them at the compressor inlet. As in the case of the high pressure architecture, a valve controls the flow through the low pressure EGR duct by using the air mass flow measurement.
If possible, check the movement of the valve stem at 1500 to 2000 rpm. The valve stem should move if the valve is functioning correctly – if not, and there`s vacuum, there`s a fault. Apply vacuum directly to the EGR valve using either a hand vacuum pump or scan tool depending on the type of EGR valve.
The EGR valve is activated by the engine control unit. The exhaust gas recirculation rate is controlled depending on the engine speed, coolant temperature and engine load. Solenoid to a fused voltage supply, battery or power supply, connect with 12.0 to 13.5 volts.
The failures are usually caused by a build-up of deposits in the EGR valve over a period of time that causes them to stick. This build-up is part of the ordinary operation of the vehicle and should be regarded as a serviceable item requiring repair or replacement.
Car care experts recommend cleaning your car`s EGR valve after driving 45,000 to 50,000 miles to maintain it better.
An average car`s EGR valve has a lifespan of approximately 10 years in service. Proper maintenance of the valve is a must if you want to avoid any performance related issues on your car. If you notice a smell of fuel that comes out from under the hood or rough idling, then it might be time to replace the valve.
The EGR valve is activated by the engine control unit. The exhaust gas recirculation rate is controlled depending on the engine speed, coolant temperature and engine load.
You can try spraying an EGR cleaner into the valve while the engine is on and revving at 2000 RPMs. Don`t spray too much at one time, however. Allow the engine to recover between sprays. And wear gloves as well—the spray is meant to remove carbon particles, so imagine what it will do to your skin!
On some heavy duty engines the EGR mass flow is directly measured with a Venturibased sensor and a closed loop control system maintains EGR flow. However, on most light duty diesel engines the EGR mass flow must be estimated.
Increased NOx emissions: when the EGR valve remains shut, the resultant high temperatures in the combustion chamber will leave a lot of unburned fuel in the exhaust, leading to increased NOx emissions and reduced fuel efficiency.
EGR Deletes and Horsepower. People want EGR deletes mainly to boost horsepower and increase performance. However, whether deleting the EGR boosts horsepower is not a simple question. First, the EGR works with other systems so that an EGR delete can result in reduced horsepower.
Deleting or disabling your EGR is unlikely to add horsepower because it only provides a slight change to the air contents of your engine`s combustion chambers. While EGR deletes do provide a purer air-fuel ratio, the difference is minor, and any horsepower gains will be small – likely in the range of 0-5 HP.
To Clean A Mechanical EGR Valve

Remove the vacuum hose and inspect closely for wear (cracks or weak spots), then clean out the carbon deposits either with a spray can of carburetor cleaner or with a pipe cleaner if the deposits are hardened or compacted.

The specific heat of the EGR is much higher than fresh air, hence EGR increases the heat capacity (specific heat) of the intake charge, thus decreasing the temperature rise for the same heat release in the combustion chamber, %EGR = volume of EGR total intake charge into the cyclinder × 100.
Engine overheating: if coolant flow is restricted, the EGR cooler is unable to cool the exhaust gases. This not only allows NOx emissions to continue, it also causes overheating which can cause serious damage.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

EGR code, Cylinder 4 misfire code 0304 detected.
ANSWER : Hi there. The Exhaust Gas Recirculation (EGR) valve may be not designed for the emissions requirements for U.S. standards. If the EGR is pulling from cylinder number 4 and after replacing the EGR and the computer detects a misfire, then the EGR is malfunctioning and not responding. When you close off the tube to the EGR and the EGR light comes on and the misfire light goes out, then the EGR is not responding to your emissions system. I recommend replacing the EGR with the OEM specified part for the engine and all of the issues should go away. If you need further assistance with your misfire and EGR, then seek out a professional, such as one from Your Mechanic, to help you.

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EGR code and Cylinder number 4 misfire detected.
ANSWER : Hi there. The Exhaust Gas Recirculation (EGR) valve may be the wrong one or the cheap design could be not designed for the emissions requirements for U.S. standards. If the EGR is pulling from cylinder number 4 and after replacing the EGR and the computer detects a misfire, then the EGR is wide open and not responsive. It is clearly the EGR as when you close off the tube that the EGR light comes on and the misfire light goes out. I recommend replacing the EGR with the OEM specified part for the engine and all of the issues should go away. If you need further assistance with your EGR and misfire, then seek out a professional, such as one from Your Mechanic, to help you.

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P0401: EGR Sensor A curcuit low
ANSWER : You should clear the codes and monitor the signal return using scanner data for DPFE and disconnect sensor to see if you read between 4 and 5.5 volts. If okay then reconnect sensor and clear the codes. Then cycle key and turn on ignition to run position for more than 5 seconds before starting for PCM to calibrate the DPFE sensor input. Then road test to see if code returns? If code returns then you may have a PCM that is at fault and will need additional pinpoint testing.

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Car stalls and P0401 insufficient egr flow
ANSWER : The P0401 code is for low EGR flow, but would not be the cause of the stalling if the flow was too low. You also state the problem is when the engine is cold and goes away after it is warm. The EGR system does not start working until the engine is warm.

It sounds like you are having a problem with the transmission or torque convertor. Have a mechanic that knows transmissions check the vehicle when it is cold to see if the engine or transmission is the problem. Sometimes the transmission seals will leak internally causing these problems until the fluid warms up. If you want to have this checked, a technician can diagnose your Check Engine Light and stalling issue thoroughly to determine what repairs will resolve your car problems.

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CODE;EGR LOW FLOW
ANSWER : Typically, on this engine there will be a blockage, consisting of hard packed carbon, in the passageway in the plenum. It can be very difficult to clean out those passageways on the vehicle without removing the aluminum plenum for a thorough inspection. I have also seen the valve fail sequentially so it would not surprise me if the "newer" valve tests bad. You can test it on or off the vehicle. If you actuate (open) the valve at idle and there is no engine stumbling, that means the valve is not functional and/or the passageway through the plenum is blocked. I would first test the valve (replace as necessary) and thoroughly clean the plenum and see if that resolves it. Other causes of Diagnostic Trouble Code P0401 include a vacuum restriction to the MAP sensor, excessive back pressure in the exhaust system, any cause of low engine vacuum, and exhaust system leaks. If you want this issued diagnosed by a certified mechanic, dispatched by YourMechanic right to your location, please request an EGR system diagnostic/valve inspection and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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New EGR Transducer Leads To Other Issues?
ANSWER : Hi there. Look to see where the EGR (Exhaust Gas Recirculation) is plumed into the engine. If the EGR is plumed into the cylinder number 3 and the EGR has a leak, then the cylinder number 3 will be weak and cause a misfire. If the EGR is plumed into the exhaust pipe, then the spark plug on the cylinder number 3 could have failed as the engine changed in temperature when replacing the EGR transducer. If you need further assistance with your engine misfire, then seek out a professional, such as one from Your Mechanic, to help you.

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Engine is running rough and P0401, P0171 and P0174 codes.
ANSWER : The first thing to check is to see if the EGR solenoid will release the vacuum when the electrical connector is disconnected. If it still doesn’t release the vacuum then the solenoid should be replaced. The codes need to be cleared and the vehicle should be driven to see if any of the codes come back.

The EGR solenoid has a small foam filter on the vent side and it is there to keep dirt out of the valve. If dirt gets into it, the solenoid will be held open and allow vacuum to pass through it. If you find that the solenoid is not leaking vacuum when the connector is disconnected then you may have a problem with the DPFE telling the ECM to open the valve. From what it seems like, I think you will find the solenoid is going to be the problem. I’d recommend having a certified mechanic check your vehicle out, they will be able to properly diagnose your Check Engine Light codes and make the necessary repair.

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1998 Mazda protege: Had the EGR valve replaced, cleared the computer codes, still get the check engine light then a EGR problem co
ANSWER : Code P0400 does not necessarily mean that there is something wrong with the EGR valve itself. The only way to condemn the EGR valve is to directly test it. In particular Code P0400 includes a circumstance where the EGR passages are simply blocked with carbon and thus little or no exhaust gases can flow into the intake manifold. Code P0400 also includes the possibility that the EGR valve is not opening due to no vacuum opening the valve from the EGR control solenoid. If the valve is electronically controlled, there could be a fault in the circuit. If your vehicle is equipped with an EGR temperature sensor, if the sensor is plugged with carbon, it can’t register a temperature change when the EGR valve is opened, signifying flow. The point is Code P0400 can never be interpreted as the EGR valve has failed. The only way to determine if an EGR valve has failed is to directly test the valve. To resolve this, that is perform a complete system diagnostic and find the root cause for the code having set, the recommended service is an EGR system diagnostic. If you request that service, the responding certified mechanic will get this fully resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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