Code 31 after EGR valve and position sensor replacement
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Mountain Pass
Joined: May 2017
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Code 31 after EGR valve and position sensor replacement
Recently had my '90 302 down to a short block and on the build back up I replaced most sensors and what have you just on the principle that (mostly) everything original. Now with both a new EGR valve and position sensor I am getting a code 31 that I was not before. I even tried a old sensor I had around (can't find where I put my old valve unfortunately). What I do find odd is that the new valves seem to have a lip on the top the old one didn't. I backprobed the sensor and it does indeed drop below .24 volts with both sensors. Whats also odd is when putting the old sensor into the old valve (this is on a engine from a old truck of mine, studs are all snapped and is rather yucky) but the plunger on the sensor does start to to compress on the old valve just a bit as installed where as with the new valve it doesn't seem to compress at all.
Any ideas?
Any ideas?
Fleet Owner
Joined: Oct 2005
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From: Kentucky
The EGR Valve Position (EVP) should be slightly compressed when you install it. Sounds like the new valve is not correct or made wrong. Usually with the newer EVP sensors on the old EGR valve you will get Code 34 since the plunger tends to be too long.
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Mountain Pass
Joined: May 2017
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Thats what I thought! Problem is, I can't seem to find any EGR valves that don't have this weird little riser on them where the sensor mounts. Both EGR valve and sensor are new. Valve is a dorman and sensor is a Stand Motor Part I believe
Fleet Owner
Joined: Oct 2005
Posts: 20,786
Likes: 1,751
From: Kentucky
I cast a leery eye towards anything with a Dorman name on it. Their QC is VERY spotty. Given many EVP sensors these days are already known to have a plunger that is too long you have a double whammy. Keep the EVP, return that Dorman EGR IMHO.
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Mountain Pass
Joined: May 2017
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Every other aftermarket EGR valve seems to be the same.
Fleet Owner
Joined: Oct 2005
Posts: 20,786
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From: Kentucky
Do not know what to tell you other than many have stated their replacement EVP sensor tends to trigger Code 34 since the plunger is too long. Now it seems the aftermarket EGR valves do not conform to the OEM specifications with no choice to use an OEM version. If it were mine I would put the old EGR and EVP back on then call it a day.
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Mountain Pass
Joined: May 2017
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Likes: 9
Do not know what to tell you other than many have stated their replacement EVP sensor tends to trigger Code 34 since the plunger is too long. Now it seems the aftermarket EGR valves do not conform to the OEM specifications with no choice to use an OEM version. If it were mine I would put the old EGR and EVP back on then call it a day.
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Fleet Owner
Joined: Oct 2005
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From: Kentucky
Tolerances are stacked against in your scenario. Is it worth swapping the new EGR valve for a replacement...maybe.
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Mountain Pass
Joined: May 2017
Posts: 102
Likes: 9
Well I found a OE looking new in box EGR valve on eBay, will report back when I get it installed
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Mountain Pass
Joined: May 2017
Posts: 102
Likes: 9
Well, I got the new EGR valve installed and used the "spare" position sensor I already had (the new sensor still was not compressing at all in idle position) and what do you know? No CEL. All drivability problems are gone. The incorrectly made EGR is on the left, and the properly made one is on the right. The box is from the 90s I'm guessing. Listing said it was in a lot of parts from a closed parts store. I could not find a "new" valve without that "spacer". This was very clearly never installed so I'm not worried about it. Hopefully this helps out someone else in the future.
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Mountain Pass
Joined: May 2017
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I don't think the spacer can come off. I tried both sensors with the spacer style valve and both read out of range, the new one being black and the spare being grey
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