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Car Forum / Honda Cars / March 2008Code P1491 insufficient EGR valve lift 98 Civic HX MT
This code (P1491 or MIL 12) begins to come up when the weather turns cold. The code reader says "insufficient egr flow". The svc manual says insufficient egr valve lift. Two ways of saying the same thing. It generally surfaces on the first really cold day when it is damp. It is the only code currently in the ecu. It has done it every winter since it was three years old. I would like to get it to go away permanently. Resetting makes it go away for 2-3 start cycles and then it is back. Is there anyway I can get it to stop short of replacing the egr assembly? Take it apart and clean carbon? Spray carb cleaner? Does any body else have this problem with the MT Civic HX D16YT5 engine? We just replaced the primary oxygen sensor just before it started setting this code but I don't think the two are related because it has done it before. 1988 Civic DX retired with 234K due to extensive rust and gas tank problems 1998 Civic HX MT with 138K  SignaturePickleman halfsour@roadyourpantsrunner.com Please remove "yourpants" to reply > This code (P1491 or MIL 12) begins to come up when the weather turns cold. > The code reader says "insufficient egr flow". The svc manual says [quoted text clipped - 15 lines] > 1988 Civic DX retired with 234K due to extensive rust and gas tank problems > 1998 Civic HX MT with 138K Is the EGR still vacuum-operated in that car? It could be a failing vacuum diaphragm or leaky vacuum line to it. 12/19/07 19:5212/19/07 19:52soundy106@gmail.com >> This code (P1491 or MIL 12) begins to come up when the weather turns cold. >> The code reader says "insufficient egr flow". The svc manual says [quoted text clipped - 18 lines] > Is the EGR still vacuum-operated in that car? It could be a failing > vacuum diaphragm or leaky vacuum line to it. It seems like that would cause a hard code at all times of the year and all weather conditions. This only shows up in cold weather. I think it is vacuum operated but controlled electrically via a solenoid valve. SignaturePickleman halfsour@roadyourpantsrunner.com Please remove "yourpants" to reply > It seems like that would cause a hard code at all times of the year and > all > weather conditions. This only shows up in cold weather. > I think it is vacuum operated but controlled electrically via a solenoid > valve. Just a guess, but maybe in the colder weather, the (I assume rubber) vaccum line to the EGR valve gets harder and leaks at one end or the other, but when it's warmer, it's able to stay pliable enough to hold vacuum. Maybe it's dried out at either end and split a little bit, and is right on the edge of leaking all the time. The solution will come when you stop trying to psyche out the temperature and pull the valve. Check for carbon build up in the ports to the valve and the valve. The next problem you will see by running a long time with a defective egr will be Catalytic converter efficiency as the exhaust gases wipe out the converter.... >> It seems like that would cause a hard code at all times of the year and >> all [quoted text clipped - 7 lines] > vacuum. Maybe it's dried out at either end and split a little bit, and is > right on the edge of leaking all the time. > This code (P1491 or MIL 12) begins to come up when the weather turns > cold. The code reader says "insufficient egr flow". The svc manual > says insufficient egr valve lift. Two ways of saying the same thing. No. Insufficient /flow/ is a different error code, P0401. Your flow is probably still within limits, but the valve is starting to stick. It might even be the valve lift sensor at the top of the EGR valve, which may be giving incorrect information to the ECM. There is an extensive testing procedure outlined in the factory shop manual. > It generally surfaces on the first really cold day when it is damp. Check the electrical connector at the EGR valve. Make sure the wires aren't internally cracked, and aren't corroded. > It > is the only code currently in the ecu. It has done it every winter [quoted text clipped - 4 lines] > Is there anyway I can get it to stop short of replacing the egr > assembly? Take it apart and clean carbon? Spray carb cleaner? See above. I don't know if this valve can be cleaned or not. SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ 12/20/07 7:3212/20/07 7:32tegger@tegger.c0m >> This code (P1491 or MIL 12) begins to come up when the weather turns >> cold. The code reader says "insufficient egr flow". The svc manual [quoted text clipped - 25 lines] > > See above. I don't know if this valve can be cleaned or not. Thanks for your help. It is interesting that the code definition in the code reader (code scout 1500 by auto x-ray) would be different than the definition in the service manual. If I ever get this figured out I will post an update. It doesn't seem to effect the drivability or mileage at all. The car seems to have more power and pep since we replaced the oxygen sensor though. SignaturePickleman halfsour@roadyourpantsrunner.com Please remove "yourpants" to reply > Thanks for your help. It is interesting that the code definition in > the code reader (code scout 1500 by auto x-ray) would be different > than the definition in the service manual. The code you have is an "enhanced" Honda-specific code. It is not an EPA mandated code. The software in that reader may not have been programmed by someone who actually knew what Honda wanted the text for the code to say. The upshot: The alphanumeric code is significant, any text given is not. Unless the reader is specifically sold as being compatible with Honda "enhanced" codes. > If I ever get this figured > out I will post an update. That would be nice. Not everybody bothers to do that. SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ Well I promised a follow up to this saga and here it is. First the 1998 HX MT with the D16Y5 engine has an EGR valve that is controlled by electric wires only-no vacuum hoses that I can see. The automatic trans version of the engine does have a solenoid controlled vacuum hose according to the shop manual. There are only 5 wires on the MT version that plug into the top of the EGR valve and no hoses. I simply pulled the connector off and put a scant drop of ProGold G100L "connector and contact conditioner" on each female connector. This kind of contact conditioner can be purchased from Cyberguys or similar computer supply houses and is used to treat the gold contacts on ram chips and pci cards. I then gave each male connector a TINY twist of about 1 or 2 degrees using a very small pair of bent tip needle nose pliers ( a trick I learned as a tech at the Honda school) and replaced the connector. Reset the ECU with my scan tool and drove it. It usually set another P1491 code within a day or two after clearing the code but it has been 10 days without it coming back. I have my fingers crossed. I think that we are dealing with very small differences in voltage or resistance here and crappy connections signal the ECU that the "EGR valve lift sensor" has detected insufficient lift. Remember this is only for the HX manual transmission for the D16Y5 engine. I was going to pull the EGR valve right off to clean carbon off but the nuts or bolts that hold it down are recessed under the base like the old carbs nuts were tucked under the base of the carb and one needed a special U-shaped wrench to remove them. It was too cold to attempt that now so I just did the above mentioned procedure and I think it worked. 12/19/07 14:3912/19/07 14:39halfsour@roadrunner.com > This code (P1491 or MIL 12) begins to come up when the weather turns cold. > The code reader says "insufficient egr flow". The svc manual says [quoted text clipped - 15 lines] > 1988 Civic DX retired with 234K due to extensive rust and gas tank problems > 1998 Civic HX MT with 138K SignaturePickleman halfsour@roadyourpantsrunner.com Please remove "yourpants" to reply Well the good luck didn't last. It set another codes P1491(insufficient lift detected) AND another code on top of it P0401 which is also EGR related (insufficient flow). I have ordered another EGR valve and gasket and will replace and clean the EGR port and report back. 12/19/07 14:3912/19/07 14:39halfsour@roadrunner.com > This code (P1491 or MIL 12) begins to come up when the weather turns cold. > The code reader says "insufficient egr flow". The svc manual says [quoted text clipped - 15 lines] > 1988 Civic DX retired with 234K due to extensive rust and gas tank problems > 1998 Civic HX MT with 138K SignaturePickleman halfsour@roadyourpantsrunner.com Please remove "yourpants" to reply Well it didn't do much good. The P1491 code is pretty much gone but I still get a code P0401 EGR insufficient Flow. It sets the second or third time we drive after clearing the code. I tried removing the EGR valve and cleaning the ports with a length of heavy duty nylon string trimmer string with a beveled tip and serrations on the side. It did the hole that went to the exhaust manifold alright but the other side leading to the intake manifold seemed to have some kind of obstruction. We tried to soften up the carbon with carb cleaner but nothing worked. I did some more research after noticing some bolts on a plate under the fuel injection rail. The plate covers the EGR "runner" opening leading to the 4 cylinders. I have ordered the gasket for this plate, the EGR valve and all the injector gaskets and o rings so I can remove the fuel rail and the plate and clean the carbon out once and for all. This seems to be a setup that is not unique to the D16Y5 engine in the '98 Civic HX. I am pretty sure this will do the trick. This is part number 11 and 12 in the intake manifold section of most Honda parts diagrams or see this link. http://www.hondapartscheap.com/southbay/jsp/prddisplay.jsp?hidSwitch=Switch& hidIrno=%7C011&catcgry1=CIVIC&catcgry2=1998&catcgry3=2DR+HX&catcgry4=KA5MT&c atcgry5=INTAKE+MANIFOLD+%282%29&vinsrch=no&ListAll=&prdrefno=&act=&count=0&q uantity=0 I have a good quality digital camera and will take pictures of the process. Can anyone offer suggestions as to where to post them? 1/17/08 13:021/17/08 13:02halfsour@roadrunner.com > Well the good luck didn't last. It set another codes P1491(insufficient lift > detected) AND another code on top of it P0401 which is also EGR related [quoted text clipped - 22 lines] >> 1988 Civic DX retired with 234K due to extensive rust and gas tank problems >> 1998 Civic HX MT with 138K SignaturePickleman halfsour@roadyourpantsrunner.com Please remove "yourpants" to reply <snip> Quite an adventure you've had. Are you yet thoroughly disgusted by the abomination that is EGR? It seems eventually to cause nothing but trouble for just about everybody. What I don't get is why some cars seem to be able to manage their NOx emissions without EGR and some don't. This is true even when the only difference between them is the type of transmission. > This is part number 11 and 12 in the intake manifold section of most > Honda parts diagrams or see this link. [quoted text clipped - 5 lines] > atcgry5=INTAKE+MANIFOLD+%282%29&vinsrch=no&ListAll=&prdrefno=&act=&coun > t=0&q uantity=0 My goodness, such URL butchery. You must be using Outhouse Express to be able to achieve such carnage. Let's fix that URL: <http://www.hondapartscheap.com/southbay/jsp/prddisplay.jsp?hidSwitch=Switch&hidI rno=%7C011&catcgry1=CIVIC&catcgry2=1998&catcgry3=2DR+HX&catcgry4=KA5MT&catcgry5= INTAKE+MANIFOLD+%282%29&vinsrch=no&ListAll=&prdrefno=&act=&count=0&quantity=0> > I have a good quality digital camera and will take pictures of the > process. Can anyone offer suggestions as to where to post them? There are a number of sites, such as Photobucket www.photobucket.com where you can upload stuff for free. You can search this group for some recent postings where people have used other sites for that purpose. Alternatively, you can send me the pictures and a writeup, and I can put it up on my site, text and all. Contact me by email if you wish to go that route. SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ 2/25/08 21:322/25/08 21:32halfsour@roadrunner.com > Well it didn't do much good. The P1491 code is pretty much gone but I still > get a code P0401 EGR insufficient Flow. It sets the second or third time we [quoted text clipped - 52 lines] >>> 1988 Civic DX retired with 234K due to extensive rust and gas tank problems >>> 1998 Civic HX MT with 138K Well I did manage to get a definitive answer on how to get rid of these codes. I documented the repair with photos and text and with the kind assistance of Tegger we have posted the whole thing to the Unofficial Honda/Accura Usenet FAQ. http://www.tegger.com/hondafaq/index.html Tegger has announced the update of the FAQ site on this and other newsgroups but I thought I would provide a link directly to the page under the original thread in the hope that the fix might be easier to find for those who come in late on the thread. Here is the direct link to the treatise on the EGR repair to this 1998 Civic HX MT VTEC-e engine (D16Y5). http://www.tegger.com/hondafaq/egr-fix/index.html Thanks for all the support from this group. It was a pleasure to give back and kudos to Tegger for the hours of attention he gave to this project. SignaturePickleman halfsour@roadyourpantsrunner.com Please remove "yourpants" to reply 1988 Civic DX retired with 234K due to extensive rust and gas tank problems 1998 Civic HX MT with 138K 2000 CRV EX MT with 98K I forgot to mention that we did replace the EGR solenoid/valve and gasket to get rid of the P1491 code. It did not go away by itself. This post is slightly out of sequence to my prior post. 1/17/08 13:021/17/08 13:02halfsour@roadrunner.com > Well the good luck didn't last. It set another codes P1491(insufficient lift > detected) AND another code on top of it P0401 which is also EGR related [quoted text clipped - 22 lines] >> 1988 Civic DX retired with 234K due to extensive rust and gas tank problems >> 1998 Civic HX MT with 138K SignaturePickleman halfsour@roadyourpantsrunner.com Please remove "yourpants" to reply
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