Check Engine Light

[jkosasih]

Hi Everybody, I have 96 ES300 with 178K miles, runs very well until lastweek the check engine light came on, however car drive and feel just like usual nothing seem to be a problem, so get it check and come up with code PO401 which is insufficient flow on EGR, took it a part clean it out really good, check the EGR using the pump test and the car begin to hesitate which is telling me that the EGR is good, I clean the EGR modulator and check all the hoses seem to be good condition, test drove no problem, however after you run about 30miles than stop about 10minutes then start the engine again and drive about 4 miles, the check engine light came on again. Once your reset the computer (pulling the EFI fuse) it will do the samething again and again. Could it be the EGR tempature sensor that causing this? Please help me out guys. Thank You in advance

[SKperformance]

There are egr problems that usually happen as many stick in po402 which is exessive egr flow.

Never seen one with insufficent flow.

Did the vacum hose work properly

[jkosasih]

Thanks skperformance, yes the vaccum works, everything works fine, I have no idea why the check engine light keep coming on, I have cleaned the egr valve, egr modulator, even the hose is good. I have this car with 178K miles, at 170K valve start to made some click noise, so I adjusted it by changing the right stem, now is smooth but at 8K miles later the check engine light came on and I check with the scanner, give me a code PO401(insufficent flow on EGR).

[jkosasih]

Found the solution, the EGR modulator had a bad valve, replace it cost $76.00. The EGR Modulator is connected to the EGR Valve. Clear the code and now working great no more check engine light. So if anyone who has code PO401(EGR insufficient flow) test your EGR Valve first make sure is working and not cloged, then if it still on the check engine light the modulator will be the one that cause check engine light. ;)

[MATATAN.8M.com]

hey jkosasih,

I have a '97 Camry with the same code 'PO401'. How did you figure the EGR vacuum Modulator was the problem, and has the check engine light stayed OFF since the replacement? And if you happened to know how many miles is a drive cycle, please let me know.

ThanX

[JPI]

Replace it with a new unit. The EGR unit is stuck open that is why you are getting the excessive flow.

www.jpimportz.org

[jkosasih]

Hi Matatan, Yes check engine light is off till now. First I check the EGR by using the vacumm and is working properly (the engine start stumble when you start vacumm) so the modulator that cause the check engine light problems, the valve quit working at 178K miles, now already 180K with no problem just the instrumental light just went out, but I already replaced it. Good Luck

[saltyreefguy]

i have the same situation, but i did replaced the modulator, egr responding normal, but cel came back, i only pull the battery for about 10 minutes, the cel came with 5 to 10 mins. so i was thinking how to check the vaccum sensors since they are attached to modulator/egr. do you guys know how its done.? jko. did do that while you were trying to fix your problem.

[SupraMan]

I had a check engine light come on 600 miles from home on my 2800 mile Thanksgiving trip ... YUK! Found out that not all Advance Auto shops do a free read/reset the OBD, this was a $42.00 deal. No big deal, let me know it wasn't anything serious. just the 0401 code dealing with insufficient EGR flow (like yours). I did an EGR clean (along with the IAC) recently, so clogged ports there wasn't the problem. They said to change the VSV, which I did ... still the light after the reset. :chairshot: The regulator was next to be replaced AFTER I read the threads here when I got home. That half baked kinda solution cost me $130 on a new workshop spares shelf part ~ if you need this component, I have a new one ... cheap! :D The satisfaction of doing the repair successfully was just as great as getting a pointer or two from the experts here in the forum to make it happen. Rather than getting 'a pointer' to the Lexus garage cash register which would have probably replaced my EGR system, plus labor. Thanks guys once again.

[kaosfive2005]

interesting a wweek ago the check engine light came on and had it looked at it was the 0401 code, i know nothin bout cars and they were sayin they'll clean it and put it together for 120 so i guess i got ripped on that..wonderful but they did smash my key up somehow and they said they'll pay for replacing it which is good, i havent paid em yet for the service but maybe i can negotiate a lower price.