Code 31
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Laughing Gas
Joined: Jan 2023
Posts: 1,172
Likes: 114
Code 31
I have a 1988 F150. I just replaced the EGR and EGR tube. Now I have a check engine light.
KOER I have code 44 then 31.
The code 44 has been there for a very long time but the 31 is new.
The EGR, and EGR tube is new. And the exhaust valve regulator solenoid was replaced with a standard motor products one about a year ago. Same with the EVP sensor. I was having a code 34 then (not now) which the EVP fixed that. I have the original motor craft solenoid still since that was not bad.
Im thinking neither sensor is likely to be bad but know that there’s still a possibility. But I wanted to ask where should I start the diagnostic process? I want the check engine light off. I’m not sure anything about the code 44 though, which isn’t what is triggering the light because that has been there for a very long time, although it is the first code, 31 is the second code to show up.
KOER I have code 44 then 31.
The code 44 has been there for a very long time but the 31 is new.
The EGR, and EGR tube is new. And the exhaust valve regulator solenoid was replaced with a standard motor products one about a year ago. Same with the EVP sensor. I was having a code 34 then (not now) which the EVP fixed that. I have the original motor craft solenoid still since that was not bad.
Im thinking neither sensor is likely to be bad but know that there’s still a possibility. But I wanted to ask where should I start the diagnostic process? I want the check engine light off. I’m not sure anything about the code 44 though, which isn’t what is triggering the light because that has been there for a very long time, although it is the first code, 31 is the second code to show up.
Hotshot
Joined: Jun 2015
Posts: 12,784
Likes: 2,422
As you probably already know, you are supposed to start with KOEO codes and repair those faults before moving on to KOER so are you also getting those codes KOEO? What do you mean by that code being there a long time? Does that mean you clear the memory and it returns or are you chasing a fault that has long since been repaired?
Cargo Master
Joined: Aug 2021
Posts: 2,251
Likes: 740
From: Maryland
How to test the EVP sensor https://www.fullsizebronco.com/threa...cement.218407/
I've heard of people having to adjust the sensor, by changing the gasket thickness, or by filing the center pintle.
I've heard of people having to adjust the sensor, by changing the gasket thickness, or by filing the center pintle.
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Laughing Gas
Joined: Jan 2023
Posts: 1,172
Likes: 114
I have to pull KOEO codes again. But 44 has been in the computer a long time. I haven’t unplugged the battery in awhile, but it has been there and it does come back when the battery gets unplugged. From the last time I pulled KOEO codes (not last night but the one before). At that time it showed 32 not 31 for KOER. Yesterday it changed to 31.
KOEO:
“O” and “C” code for 31
I will test the sensor later today or sometime tomorrow then. I’ll try to see if I need to adjust it to.
KOEO:
“O” and “C” code for 31
I will test the sensor later today or sometime tomorrow then. I’ll try to see if I need to adjust it to.
Thread Starter
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Laughing Gas
Joined: Jan 2023
Posts: 1,172
Likes: 114
Will my exhaust leak from the bad passenger exhaust manifold cause a code 44? Cause I figure the oxygen it sends into the exhaust is getting right back out where the manifold isn’t sealed. Cause it checks the o2 sensor for that right?
I was gonna go test the EVP sensor in a bit.
I was gonna go test the EVP sensor in a bit.
Logistics Pro
Joined: Nov 2013
Posts: 3,922
Likes: 1,192
From: Mojave, Ca
Code 44 happens when the AIR valve opens and the computer doesn't see the o2 sensor report lean from the additional fresh air hitting the O2 sensor. A leaking exhaust manifold could cause this.
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Laughing Gas
Joined: Jan 2023
Posts: 1,172
Likes: 114
I tested the EVP
The harness gives 4.9v. So that’s good
The sensor has 3,960 ohms between the middle and right pin
And 400 ohms between the left and middle pin.
The sensor and power passes. Now what?
I removed and reinstalled the EVP sensor, thinking maybe the O-Ring didn’t seat right. Then disconnected the battery for 5 minutes. It changed from a code 31 to a code 32 KOEO.
The harness gives 4.9v. So that’s good
The sensor has 3,960 ohms between the middle and right pin
And 400 ohms between the left and middle pin.
The sensor and power passes. Now what?
I removed and reinstalled the EVP sensor, thinking maybe the O-Ring didn’t seat right. Then disconnected the battery for 5 minutes. It changed from a code 31 to a code 32 KOEO.
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Laughing Gas
Joined: Jan 2023
Posts: 1,172
Likes: 114
I just applied vacuum with a hose I attached to the EGR and had the middle wire of the EVP back probed, the signal did not change from 0.56 when I pushed the pin on the sensor all the way in.
So that means my new sensor is dead right?
So that means my new sensor is dead right?
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Laughing Gas
Joined: Jan 2023
Posts: 1,172
Likes: 114
Ok I figured out the problem. Now how to fix it? The EGR is a Dorman one from rockauto. And the EVP is a Napa one. It sits at 0.00v if I apply the slightest amount of vacuum it goes up to 0.02 and goes up from there. So the pin and diaphragm are not touching. How do I make them touch? And the right amount.
Edit: just returning EGR for a new one
Edit: just returning EGR for a new one