Check Engine light on
#1
04-15-2009, 03:21 AM
Check Engine light on
i have a 1997 camry le 2.2liters i just bought and when i 1st bought it, it failed smog.. so now the check engine light popped up and said P0401 egr code means insufficient egr flow i replaced the egr valve and its still on.. im not a mechanic so im just trying to get it fixed right so i can smog my car =)
#2
04-15-2009, 12:16 PM
Suggest you visit the AutoZone website at www.autozone.com. You may have to setup a password, etc but the site is free. The site has a great deal of info on auto repairs in their vehicle repair guides.
Did you clean the steel exhaust gas tube that ran to the EGR valve? The tube often becomes clugged with carbon.
The EGR valve is turned on and off by a vacuum modulator controlled by a 12V DC electric vacuum valve (VSV). This valve could be bad or the wiring going to it.
The autozone site should have info on testing the VSV valve.
Most likely it is the VSV valve or a plugged tube.
Did you clean the steel exhaust gas tube that ran to the EGR valve? The tube often becomes clugged with carbon.
The EGR valve is turned on and off by a vacuum modulator controlled by a 12V DC electric vacuum valve (VSV). This valve could be bad or the wiring going to it.
The autozone site should have info on testing the VSV valve.
Most likely it is the VSV valve or a plugged tube.
#3
05-10-2009, 01:28 PM
You'll need a vacuum pump/gauge to verify EGR operation. Install the gauge to the single vacuum nipple leaving the EGR modulator and race the engine. If you show an increase of vacuum (up to 18in/hg)- that section of the EGR system is working. Now take the hose from the single nipple you just disconnected and apply vacuum with the engine running at idle. The engine should NOT stall as the VSV should be set to vent this vacuum. If its stalls- the VSV is stuck on. You'll need to replace the VSV which is in a very difficult location to reach.
The reason why you get a "low flow" code is that the system uses the MAP sensor to check EGR operation under certain conditions. Under these conditions, MAP sensor voltage is monitored. At this time- EGR is operated by the ECU which look for a change is MAP sensor output (which is normal). If there is no change in output- the EGR is thought to be inoperational. Since the VSV is stuck ON- and the EGR is always operating- NO CHANGE is detected in the MAP sensor readings from when the EGR was off to being switched ON-
JJ
The reason why you get a "low flow" code is that the system uses the MAP sensor to check EGR operation under certain conditions. Under these conditions, MAP sensor voltage is monitored. At this time- EGR is operated by the ECU which look for a change is MAP sensor output (which is normal). If there is no change in output- the EGR is thought to be inoperational. Since the VSV is stuck ON- and the EGR is always operating- NO CHANGE is detected in the MAP sensor readings from when the EGR was off to being switched ON-
JJ
#4
08-17-2009, 09:06 PM
i have a 1997 camry le 2.2liters i just bought and when i 1st bought it, it failed smog.. so now the check engine light popped up and said P0401 egr code means insufficient egr flow i replaced the egr valve and its still on.. im not a mechanic so im just trying to get it fixed right so i can smog my car =)
Thread
Thread Starter
Forum
Replies
Last Post
sconley
General Tech
4
03-02-2012 09:33 AM
hardyrxp
General Tech
2
04-06-2010 09:09 AM
hardyrxp
ECU & Electronics
5
03-31-2010 02:10 AM
