Code 71, Egr Problems? Read This!
01-10-13, 11:49 AM
#31
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Car has this code issue.
The Lexus I am interested in purchasing has this code problem. Owner said it doesn't affect the car. I'll fix it asap. Thanks guys, you rock! 
01-08-14, 03:07 PM
#33
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I'm currently having a cel for code71. The car seem to run fine ith it on but I wanted to fix it so I cleaned the egr valve and modulator. Now my car runs horrible.The idle is fine but now the engine shakes. Also, I have loss of power after 40mph. I have to almost wot it to get it up to freeway speed.
Does this sound like a stuck valve or something else. Vacuum leak? sureI'm dure the hoses are all placed where they're suppose to. I will buy a vacuum pump soon to test it but would like to get your guys take in this. Thanks.
Does this sound like a stuck valve or something else. Vacuum leak? sureI'm dure the hoses are all placed where they're suppose to. I will buy a vacuum pump soon to test it but would like to get your guys take in this. Thanks.
04-03-14, 10:02 PM
#34
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I'm currently having a cel for code71. The car seem to run fine ith it on but I wanted to fix it so I cleaned the egr valve and modulator. Now my car runs horrible.The idle is fine but now the engine shakes. Also, I have loss of power after 40mph. I have to almost wot it to get it up to freeway speed.
Does this sound like a stuck valve or something else. Vacuum leak? sureI'm dure the hoses are all placed where they're suppose to. I will buy a vacuum pump soon to test it but would like to get your guys take in this. Thanks.
Does this sound like a stuck valve or something else. Vacuum leak? sureI'm dure the hoses are all placed where they're suppose to. I will buy a vacuum pump soon to test it but would like to get your guys take in this. Thanks.
Any luck fixing the issue? I am wondering if this may help my issue.
https://www.clublexus.com/forums/gs-...ml#post8458939
02-12-15, 07:24 PM
#35
I also had a code 71 and have replaced the egr modulator, cleaned the silver tube, replaced the sensor that screws into the egr valve itself and I have done the "suck" test on the egr valve and the engine does go from steady idle to bogging so I assume the valve is working properly.
My check engine light is still on. Is it supposed to go off by itself or do I need to clear it some how? How do I clear it, just disconnect the battery?
My check engine light is still on. Is it supposed to go off by itself or do I need to clear it some how? How do I clear it, just disconnect the battery?
03-27-15, 05:32 PM
#36
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noob on old thred
definite EGR malfunction with no CEL or code 71.
just a heads up on failed smog for hi NOx.
this guy, Vacuum Control Valve or VCV, was leaking all vacuum and because its "teed" into the EGR vacuum modulator vacuum signal pipe, the EGR was not getting any vacuum to operate.
this is the part number that comes up: 90925-03190
hope this helps.
keep up the good werk
just a heads up on failed smog for hi NOx.
this guy, Vacuum Control Valve or VCV, was leaking all vacuum and because its "teed" into the EGR vacuum modulator vacuum signal pipe, the EGR was not getting any vacuum to operate.
this is the part number that comes up: 90925-03190
hope this helps.
keep up the good werk
04-30-15, 11:33 AM
#37
Driver School Candidate
I had the same problem and i replaced EGR valve, modulator and VSV and also put new vacuum hoses. Bt the code was still there my mechanic did the vacuum test and he found that one hose coming from throttle body was stuck and no air was passing to modulator so he cleaned the throttle body and code is gone.
07-31-15, 09:40 PM
#38
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egr delete
Someone told me that you can also do a egr delete by removing the egr and using a plate to block where it was. I'm not sure if that is a good idea because I think that it will throw all sorts of codes check engine lights for ever. Have anyone heard of this?
QUOTE=94GS300;2639034]If you have ever had your "check engine" light and "trac off" light come on because of a CODE 71 (EGR problems) then you might want to read this. I just finished fixing this problem on my car and it was not fun at all. So I figured this might help anyone else who has this problem. This is very long and very in-depth so if you don't want to read it, then you really don't want to attempt to fix this problem yourself. Some of the EGR components on this car are not easy to access!!
First, CODE 71 means there is a problem with the EGR (Exhaust Gas Recirculation) system. The car's ECU can detect if there is a problem with this system by monitoring the EGR temperature sensor. This sensor detects the temperature of the EGR system and therefore knows if there is too little exhaust gas going back into the intake or if there is too much exhaust gas going into the intake manifold.
SYMPTOMS: If you get the code and your car is running rough at idle, it probably means that there is too much exhaust gas going into the intake. That means that the EGR valve is probably stuck open. If you get the code and your car seems to be running fine, then your problem could be a number of things.
DIAGNOSING: First familiarize yourself with the locations of all the components in the EGR circuit.
EGR VACUUM MODULATOR - This is the circular disk near the firewall on the driver side that has P, Q, and R marked on top. This controls the EGR VALVE by regulating the amount of vacuum sent to the EGR valve.
EGR VALVE - This is the circular disk that is near the EGR VACUUM MODULATOR. Find Q on the VACUUM MODULATOR and follow the vaccum line connected to it and you will end up at the EGR VALVE.
VSV - This is located in right next to the intake plenum. It has two vacuum lines coming out of it and has an electrical connector on it. This overrides the EGR VACUUM MODULATOR in certain conditions.
EGR TEMPERATURE SENSOR - This is the connected to the EGR PIPE. This reads the temperature of the exhaust gas that is recirculated to the intake.
STEP 1 - To diagnose what your problem is, I would first invest in a vacuum pump with a gauge. It is well worth the money if you want to figure out your problem. Also, disconnect your battery so that the code clears and that your safe when performing all of this work. First, locate the vacuum hose that comes off of "Q" on the VACUUM MODULATOR. This line splits into two, but follow the line that goes to top of the EGR valve. Disconnect that line on the EGR VALVE and hook up your vacuum gauge to it. This will tell you if your EGR VALVE is working properly. Your engine should start to run rough at about 5" Hg. At more than 5" Hg, your engine should almost die. If nothing happens when you apply full vacuum (about 20" Hg), then either your EGR VALVE is stuck closed, your EGR PIPE is clogged, or the EGR intake inlet is clogged. This scenario is the one you don't want because it will involve lots of labor!!! Skip to Step 6 if your engine doesn't die or run really rough when doing the above test.
STEP 2 - If your car passes the above test, then you are in much better shape because your problem is most likely a bad EGR VACUUM MODULATOR, VSV, EGR TEMP SENSOR, or vacuum line. First, make sure that all of your vacuum lines connected to the VSV, EGR VACUUM MODULATOR, and EGR VALVE are in good condition and not clogged. If so, replace. If not, go to STEP 3.
STEP 3 - Check to see if you have a bad EGR TEMPERATURE SENSOR. The resistance should be 69 - 89 k ohms at 122F, 12-15 k ohms at 212F, and 2 - 4 k ohms at 302F. If the sensor doesn't meet these specs, then the computer may think that there is too much or too little EGR flow.
STEP 4 - First, check to see if you have a bad EGR VACUUM MODULATOR. To do this, take it out of the vehicle. Just remove the vacuum hoses off of "P", "Q", and "R". The slide it out of its holder. Then pull up on it to remove the vacuum hose underneath it. Once you have it out of the vehicle, plug ports "P" and "R" and blow through port "Q". Air should blow pretty freely out of the side of the cap. If not, then the filter under the cap is probably clogged. Take off the cap and check the filter. Now, put a little bit of pressure in the port on the bottom and try the above test again. You should not be able to blow air through "Q" or it should be very hard when there is pressure on the bottom port. If you are still able to blow air through it even with pressure on the bottom, then you have a bad EGR VACUUM MODULATOR. If it passed all of the above tests, then your problem probably isn't the EGR VACUUM MODULATOR.
STEP 5 - Check the VSV. Disconnect both vacuum lines on it and disconnect the electrical connector. Blow air through the port closest to the electrical connector with 12V applied to it and without 12V applied to it. You should be able to blow air through it when the 12V is applied and not able to blow air through it when no voltage is applied . If you are able to blow air through it in both scenarios or if it is blocked in both of the above scenarios, then the VSV is faulty. If it is not faulty, go to STEP 5.
STEP 6 - This is where it gets interesting!! You probably have a bunch of carbon clogging up passages. First, take off the EGR PIPE. This is the pipe that comes from the exhaust manifold and goes into the EGR VALVE. The EGR PIPE is absolutely miserable to take off. There are 2 bolts that hold it into the exhaust manifold that are near the bottom of the engine. You can't get to them from under the car, so you either have to try and snake your hand down there to loosen the bolts or you will have to use a long extension and swivel socket adapter and go at it from an angle. Once have have those two bolts off, you will see the huge nut that connects it to the EGR VALVE. Loosen that nut until the EGR PIPE comes off. Next, take off the EGR VALVE from the Intake Plenum. It is held onto the intake plenum by 2 nuts. Once you have these parts off, inspect them for carbon build up. Make sure to clean everything real good. Also, make sure you take off the elbow on the EGR PIPE that is held on by a screw. That will probably be full of carbon that can block the passage to the EGR MODULATOR. While you have the EGR VALVE out, apply vacuum to the top port and make sure the valve fully stroked and destrokes. Now, here is the judgement call you will need to make. If you found that the EGR VALVE was stuck or that any of the passages were blocked or severely restricted, you might be able to get by and just put everything back on be OK. But, since you have made it this far, you might as well do the next step or else you will be wishing you did if your code comes back.
STEP 7 - You are going to have to take off your intake plenum (the part of the intake that your EGR VALVE is connected to) and clean the passage that the EGR VALVE feeds. In order to do this, you have to remove the air intake, the throttle body, and then the intake plenum. This isn't too bad, but there are a couple nuts that are hard to get to. Also, there is a coolant bypass hose on the bottom of the throttle body that is hard to get off and back on. Once you have it apart, you will see what I am talking about. This passage makes a couple of sharp bends and then ends up in a tube with a small hole in it. You will see how easy it is for carbon to plug this up. Mine was filled with it. You will have to be pretty innovative to clean it. Try and find long pipe cleaning brushes. I used those and coat hangers to try and get from one end of the passage to the other. Cleaning the small hole in the tube is also a challenge. But make sure and spend the time and do it right because more than likely this is your problem. This was the problem on mine. When I did the EGR VACUUM test, my engine speed only slightly decreased because there was almost no exhaust gas going back into the intake. I used a couple of cleaners to help and the best one I found was the STP Intake Cleaner. It worked much better at breaking up the carbon deposits.
STEP 8 - Once you have everything clean, put it all back together. Don't forget to get new EGR gaskets for both the EGR VALVE and PIPE (same part #). Make sure to install the EGR VALVE first before installing the EGR PIPE. The EGR PIPE is very hard to install without the bottom bolts falling out or the gasket falling off. Another tip, when installing the throttle body, use a tie wrap to hold the coolant bypass clamp open so you can slide the hose onto the pipe. One you get the hose on the pipe, just take a screwdriver and pry the tie wrap off.
Hopefully this helps anyone with the annoying CODE 71. I fought this problem for a solid week and I thought I would pass this information onto someone to help. My problem was the clogged EGR intake passage. Looks like the design lends itself to carbon build up after some miles. I cleaned mine up good and everything is good as new!![/QUOTE]
QUOTE=94GS300;2639034]If you have ever had your "check engine" light and "trac off" light come on because of a CODE 71 (EGR problems) then you might want to read this. I just finished fixing this problem on my car and it was not fun at all. So I figured this might help anyone else who has this problem. This is very long and very in-depth so if you don't want to read it, then you really don't want to attempt to fix this problem yourself. Some of the EGR components on this car are not easy to access!!
First, CODE 71 means there is a problem with the EGR (Exhaust Gas Recirculation) system. The car's ECU can detect if there is a problem with this system by monitoring the EGR temperature sensor. This sensor detects the temperature of the EGR system and therefore knows if there is too little exhaust gas going back into the intake or if there is too much exhaust gas going into the intake manifold.
SYMPTOMS: If you get the code and your car is running rough at idle, it probably means that there is too much exhaust gas going into the intake. That means that the EGR valve is probably stuck open. If you get the code and your car seems to be running fine, then your problem could be a number of things.
DIAGNOSING: First familiarize yourself with the locations of all the components in the EGR circuit.
EGR VACUUM MODULATOR - This is the circular disk near the firewall on the driver side that has P, Q, and R marked on top. This controls the EGR VALVE by regulating the amount of vacuum sent to the EGR valve.
EGR VALVE - This is the circular disk that is near the EGR VACUUM MODULATOR. Find Q on the VACUUM MODULATOR and follow the vaccum line connected to it and you will end up at the EGR VALVE.
VSV - This is located in right next to the intake plenum. It has two vacuum lines coming out of it and has an electrical connector on it. This overrides the EGR VACUUM MODULATOR in certain conditions.
EGR TEMPERATURE SENSOR - This is the connected to the EGR PIPE. This reads the temperature of the exhaust gas that is recirculated to the intake.
STEP 1 - To diagnose what your problem is, I would first invest in a vacuum pump with a gauge. It is well worth the money if you want to figure out your problem. Also, disconnect your battery so that the code clears and that your safe when performing all of this work. First, locate the vacuum hose that comes off of "Q" on the VACUUM MODULATOR. This line splits into two, but follow the line that goes to top of the EGR valve. Disconnect that line on the EGR VALVE and hook up your vacuum gauge to it. This will tell you if your EGR VALVE is working properly. Your engine should start to run rough at about 5" Hg. At more than 5" Hg, your engine should almost die. If nothing happens when you apply full vacuum (about 20" Hg), then either your EGR VALVE is stuck closed, your EGR PIPE is clogged, or the EGR intake inlet is clogged. This scenario is the one you don't want because it will involve lots of labor!!! Skip to Step 6 if your engine doesn't die or run really rough when doing the above test.
STEP 2 - If your car passes the above test, then you are in much better shape because your problem is most likely a bad EGR VACUUM MODULATOR, VSV, EGR TEMP SENSOR, or vacuum line. First, make sure that all of your vacuum lines connected to the VSV, EGR VACUUM MODULATOR, and EGR VALVE are in good condition and not clogged. If so, replace. If not, go to STEP 3.
STEP 3 - Check to see if you have a bad EGR TEMPERATURE SENSOR. The resistance should be 69 - 89 k ohms at 122F, 12-15 k ohms at 212F, and 2 - 4 k ohms at 302F. If the sensor doesn't meet these specs, then the computer may think that there is too much or too little EGR flow.
STEP 4 - First, check to see if you have a bad EGR VACUUM MODULATOR. To do this, take it out of the vehicle. Just remove the vacuum hoses off of "P", "Q", and "R". The slide it out of its holder. Then pull up on it to remove the vacuum hose underneath it. Once you have it out of the vehicle, plug ports "P" and "R" and blow through port "Q". Air should blow pretty freely out of the side of the cap. If not, then the filter under the cap is probably clogged. Take off the cap and check the filter. Now, put a little bit of pressure in the port on the bottom and try the above test again. You should not be able to blow air through "Q" or it should be very hard when there is pressure on the bottom port. If you are still able to blow air through it even with pressure on the bottom, then you have a bad EGR VACUUM MODULATOR. If it passed all of the above tests, then your problem probably isn't the EGR VACUUM MODULATOR.
STEP 5 - Check the VSV. Disconnect both vacuum lines on it and disconnect the electrical connector. Blow air through the port closest to the electrical connector with 12V applied to it and without 12V applied to it. You should be able to blow air through it when the 12V is applied and not able to blow air through it when no voltage is applied . If you are able to blow air through it in both scenarios or if it is blocked in both of the above scenarios, then the VSV is faulty. If it is not faulty, go to STEP 5.
STEP 6 - This is where it gets interesting!! You probably have a bunch of carbon clogging up passages. First, take off the EGR PIPE. This is the pipe that comes from the exhaust manifold and goes into the EGR VALVE. The EGR PIPE is absolutely miserable to take off. There are 2 bolts that hold it into the exhaust manifold that are near the bottom of the engine. You can't get to them from under the car, so you either have to try and snake your hand down there to loosen the bolts or you will have to use a long extension and swivel socket adapter and go at it from an angle. Once have have those two bolts off, you will see the huge nut that connects it to the EGR VALVE. Loosen that nut until the EGR PIPE comes off. Next, take off the EGR VALVE from the Intake Plenum. It is held onto the intake plenum by 2 nuts. Once you have these parts off, inspect them for carbon build up. Make sure to clean everything real good. Also, make sure you take off the elbow on the EGR PIPE that is held on by a screw. That will probably be full of carbon that can block the passage to the EGR MODULATOR. While you have the EGR VALVE out, apply vacuum to the top port and make sure the valve fully stroked and destrokes. Now, here is the judgement call you will need to make. If you found that the EGR VALVE was stuck or that any of the passages were blocked or severely restricted, you might be able to get by and just put everything back on be OK. But, since you have made it this far, you might as well do the next step or else you will be wishing you did if your code comes back.
STEP 7 - You are going to have to take off your intake plenum (the part of the intake that your EGR VALVE is connected to) and clean the passage that the EGR VALVE feeds. In order to do this, you have to remove the air intake, the throttle body, and then the intake plenum. This isn't too bad, but there are a couple nuts that are hard to get to. Also, there is a coolant bypass hose on the bottom of the throttle body that is hard to get off and back on. Once you have it apart, you will see what I am talking about. This passage makes a couple of sharp bends and then ends up in a tube with a small hole in it. You will see how easy it is for carbon to plug this up. Mine was filled with it. You will have to be pretty innovative to clean it. Try and find long pipe cleaning brushes. I used those and coat hangers to try and get from one end of the passage to the other. Cleaning the small hole in the tube is also a challenge. But make sure and spend the time and do it right because more than likely this is your problem. This was the problem on mine. When I did the EGR VACUUM test, my engine speed only slightly decreased because there was almost no exhaust gas going back into the intake. I used a couple of cleaners to help and the best one I found was the STP Intake Cleaner. It worked much better at breaking up the carbon deposits.
STEP 8 - Once you have everything clean, put it all back together. Don't forget to get new EGR gaskets for both the EGR VALVE and PIPE (same part #). Make sure to install the EGR VALVE first before installing the EGR PIPE. The EGR PIPE is very hard to install without the bottom bolts falling out or the gasket falling off. Another tip, when installing the throttle body, use a tie wrap to hold the coolant bypass clamp open so you can slide the hose onto the pipe. One you get the hose on the pipe, just take a screwdriver and pry the tie wrap off.
Hopefully this helps anyone with the annoying CODE 71. I fought this problem for a solid week and I thought I would pass this information onto someone to help. My problem was the clogged EGR intake passage. Looks like the design lends itself to carbon build up after some miles. I cleaned mine up good and everything is good as new!![/QUOTE]
10-22-18, 02:15 PM
#39
Driver School Candidate
Where is the VSV for the egr located on the 1996 LS400 model? There are 2 such valves close to the EGR valve but one connects to the Fuel Regulator, the other is connected to the top of the plenum. I suspect it would be the latter, as this is where the egr vsv was located on the earlier 1st generation LS400s.
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