Code P1490, P1491
 

Hi,

I have a 1999 Honda Accord 4cyl-VTEC, the code has been a problem for the past 4 months. After replacing spark plug, wires, distributor cap, timming belt (had to, 165k), genuine Honda EGR valve ($340), and taking it to one of the most knowledgable Honda mechanic in my area, there is no solution to my problem.

The problem is, at the start of the car in cold weather it idles fine b/c it's cold. Btw'n 2-10min of driving the and when the car comes to a stop, IT WANTS TO COMPLETELY DIE with rough idle and choking. My mechanic has performed all the tests in the Honda Manual and every test has passed including all EGR sensors and valves and wiring. He still does not know what it could be and why its only btw'n 2-10 min of driving that it wants to stall. Also, when I drive for about half an hour or more, and when I come to a stop it still rough idles.

Code P1401 and P1491 keep coming up after a reset.

Any suggestions?????????????????? I need help bad...........

RE: Code P1490, P1491
 

okay in your post title you say a 1490 and 1491, but in your post you said 1401.... which one is the typo?

RE: Code P1490, P1491
 

this may sound stupid but it has to be asked, did someone reset/clear the computer after replacing those parts? remove the negative battery cable for about 5 min....

RE: Code P1490, P1491
 

Further update just going on guesses (referanced from: http://autorepair.about.com/library/a/1f/bl260f.htm )


DTC P1491 - "EGR Valve Lift Insufficient Detected" is most often caused by a broken vacuum line going to the EGR valve. So I would check all the vaccum lines to be sure they are tight and not broken. Funny thing about vacuum lines, they never break out in the open, always behind or under something. Best way to check them is to remove them one at a time so you don't get mixed up and check them over carefully. If the vacuum lines are good, you will need to check the electronics that operate the EGR system. It is an involved procedure, much too long to include here. Go to the library, in the Reference section, and get the Motors Import Service manual. That has the complete, step by step, procedure for checking the system. Or you can get a DIY subscription to Alldata which also has the complete, step by step, procedure.

RE: Code P1490, P1491
 

and behind door #3 I'll give you this one (referance site: http://www.honda-acura.net/forums/ar...p/t-33832.html )

the egr code is thrown by either the egr lift sensor on the egr valve which is on the intake manifold, sort of between the distributor and throttle body, or the egr control solenoid which is on the vacuum tube going to the egr valve.

RE: Code P1490, P1491
 

SORRY GUYS ITS P1401 AND P1491

RE: Code P1490, P1491
 

are there any diagrams you can send in regards to these vacum lines??

RE: Code P1490, P1491
 

all good... those two options I mentioned should help you diagnose it.... my gut instinct is telling me that you've got a broken vacuum line, sensors would test fine but read wrong.... If all the hoses are in fact fine I believe that a P1401 isn't an actual/typicall honda code (I may be talking out my rear but who knows....) since it's those two I suggest reading this article as well...

http://findarticles.com/p/articles/m..._n9392559/pg_4

And watch the caps thing, it just comes accross irritating, not pleasing to the eye and it's a personal pet peeve of mine....