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Correct Voltage for EGR position sensor?


natertot

Active Member
Joined
Mar 23, 2025
Messages
29
City
Denver
Vehicle Year
1985
Engine
2.8 V6
Transmission
Automatic
I have to install emissions on my car, it's a daily driver lol. I'm getting a code 34 KOER saying that the egr is not "responding properly during test". In other manuals I see this can mean the signal is above the maximum voltage when EGR is closed (.67V). I measured it, I get .24V KOEO and .32 KOER, so that code doesn't make sense. Are these within range?

New EGR and EVP, it was plated off before. I did have to extend the pintle on the EVP with a piece of vacuum tubing because its voltage was below the minimum KOEO (that fixed code KOEO 31 for me).
 
Follow the vacuum line that goes to the EGR. You should come upon a black valve, usually mounted on the fender somewhere. See if it has a little black round plastic "hat" on the top. If it does, pull that off and see if there is a foam filter under there. If there is, it is more than likely dirty. Clean it and the problem may go away.

These vacuum systems are hard to picture, since they work in reverse. But when the valve actuates from the computer telling it to, it puts engine vacuum on the EGR valve. The EGR moves open and the position sensor verifies to the computer that it did really move. Then the computer shuts the valve off. When the valve shuts it needs to "drain" the vacuum off the line going to the EGR, so the EGR valve will shut. It does this by letting air through that little foam filter and then that relieves the EGR valve and lets it close. If that filter is dirty, then the air can't get in and the EGR valve hangs open too long. The computer wants it to shut, but it's not, so the computer throws a code.
 
Follow the vacuum line that goes to the EGR. You should come upon a black valve, usually mounted on the fender somewhere. See if it has a little black round plastic "hat" on the top. If it does, pull that off and see if there is a foam filter under there. If there is, it is more than likely dirty. Clean it and the problem may go away.

These vacuum systems are hard to picture, since they work in reverse. But when the valve actuates from the computer telling it to, it puts engine vacuum on the EGR valve. The EGR moves open and the position sensor verifies to the computer that it did really move. Then the computer shuts the valve off. When the valve shuts it needs to "drain" the vacuum off the line going to the EGR, so the EGR valve will shut. It does this by letting air through that little foam filter and then that relieves the EGR valve and lets it close. If that filter is dirty, then the air can't get in and the EGR valve hangs open too long. The computer wants it to shut, but it's not, so the computer throws a code.
Yeah when I bought it there were no vacuum lines or solenoids anywhere, it was just the starter solenoid and all else was ripped out. I’m confident I reinstalled everything properly, but I did pull the EGR solenoids from the junkyard so chances are it’s dirty, I didn’t know they had a filter! That makes a ton of sense actually. It surprises me that it would open at all at idle though (considering I saw voltage go up to .32V running from its .24V when off), I thought it would be the same since the EGR doesn’t kick in until higher rpm. I’ll give it a look on my lunch break soon!
 
Follow the vacuum line that goes to the EGR. You should come upon a black valve, usually mounted on the fender somewhere. See if it has a little black round plastic "hat" on the top. If it does, pull that off and see if there is a foam filter under there. If there is, it is more than likely dirty. Clean it and the problem may go away.

These vacuum systems are hard to picture, since they work in reverse. But when the valve actuates from the computer telling it to, it puts engine vacuum on the EGR valve. The EGR moves open and the position sensor verifies to the computer that it did really move. Then the computer shuts the valve off. When the valve shuts it needs to "drain" the vacuum off the line going to the EGR, so the EGR valve will shut. It does this by letting air through that little foam filter and then that relieves the EGR valve and lets it close. If that filter is dirty, then the air can't get in and the EGR valve hangs open too long. The computer wants it to shut, but it's not, so the computer throws a code.

I don't think this was the issue. The foam in there was old and hardened so it probably needed to be removed anyways but the difference in EVP voltage between engine off and engine on seems suspect to me as well - not sure what could be triggering that code.
 
I wouldn't know how to tell - when running and idling I don't feel any air coming out of it.
Unplug the hose on the EGR valve. Running and idling, no suction on the hose. Rev it up and you might get a little suction on the hose from the vacuum valve opening. That is when the computer is expecting a higher voltage on the EGR sensor.
 
Unplug the hose on the EGR valve. Running and idling, no suction on the hose. Rev it up and you might get a little suction on the hose from the vacuum valve opening. That is when the computer is expecting a higher voltage on the EGR sensor.
Yep, no vacuum at idle, vacuum pulls at higher rpm as expected. Is it possible that the incorrect EGR valve would cause this? That was an ebay purchase, not original. EVP I don't think is the issue, the EVP I got from autozone seems alright and so does the original.
 

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