Code 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

 

Is the EGR still vacuum-operated in that car? It could be a failing
vacuum diaphragm or leaky vacuum line to it.

 

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.

Check the electrical connector at the EGR valve. Make sure the wires aren't
internally cracked, and aren't corroded.

See above. I don't know if this valve can be cleaned or not.

 

12/19/07 19:5212/19/07 19:

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.

 

12/20/07 7:3212/20/07 7:0m

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.

 

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.

That would be nice. Not everybody bothers to do that.

 

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....

 

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:

 

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:

 

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:

 

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:

 

<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.

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&hidIrno=%7C011&catcgry1=CIVIC&catcgry2=1998&catcgry3=2DR+HX&catcgry4=KA5MT&catcgry5=INTAKE+MANIFOLD+%282%29&vinsrch=no&ListAll=&prdrefno=&act=&count=0&quantity=0>

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.

 

2/25/08 21:322/25/08 21:

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.
--
Pickleman

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