# EGR Valve and Knock Sensor



## courtjester (Nov 5, 2004)

My check engine ligh came on on me one day when I was driving home and I used the diagnostic on the ECU and it told me that the EGR valve and the knock sensor were reporting problems. Well the knock sensor I was a little confused about, I looked in the Chiltons Manual and it said that there is supposed to be a sensor connector with two wires in it for the knock sensor. I pulled the connector off and there was only one wire. This made me think it may not be working at all. The knock sensor wont turn on the check engine light so this has probably been the same way for awhile. 

The EGR valve however will set off the light. I started to check the vacuum lines and the one connected to the EGR valve had no suction. since there are so many line I tried to follow them to look for damaged lines but I couldn't see some of them and eventually gave up. I started puttin 91 octane instead od the 89 I normally put in. After two tanks of 91 went through it the check engine light went off. I put one tank of 89 in and within 5 minutes (The car had almostno gas) the check engine light went off. This is always the case. I just don't understand why what kind of gas I put in matters for the EGR valve. Does anyone know what to look at or anything else that would help?


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## BikerFry (Jul 31, 2003)

If the ECU says you're getting knock and higher octane makes it go away you might want to check your timing.


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## courtjester (Nov 5, 2004)

But the EGR Valve is what I was concearned about. That and the vacuum lines.


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## Token Moron (Mar 28, 2003)

bikerfry is right....knock sensor CEL would be because of the timing. check that ish. if the egr light comes on and off depending on the fuel used, it isnt a vacuum light..premium fuel burns better and cleaner. and lower octane does not, so maybe the egr valve is getting dirty.


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## courtjester (Nov 5, 2004)

What about the vacuum line not working? That is probably why the ECU is turning on the check engine light.


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## Token Moron (Mar 28, 2003)

a vacuum line wouldnt trigger a CEL


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## specalk99 (Apr 4, 2005)

where is the egr located ? and what does it look like? and if i open it to clean it will i need a new gasket for it ?


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## yuke (Nov 16, 2005)

*egr valve and knock sensor*

In reply to courtjester you might not have vacuum at your egr valve because maybe your vacuum control solenoid is not opening to let the vacuum go to the egr.I found on mine that if I unhooked the wires going to the solenoid that it stays open all the time and allows the egr to receive vacuum which allows it to operate.I thought when I got the egr to operate I thought I would see an increase in gas mileage which has not been the case.I currently get 23 mpg and think I should be getting more like 30.Besides the mileage the engine runs fine so I am stumped as to what to look at next.Maybe valves or crank angle sensor.


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