Code 24... fixed it and now all of a sudden code 31?

tomlson

New Member
Nov 2, 2017
3
0
0
Florida
So I had what I thought was a bad AFM, ordered a lexus afm which I just put in today. After resetting the ecu, no codes and the car ran like good. I took it for about a 5 minute test drive and everything seemed normal. I was in my driveway with the car idling scrolling through my s-afc readings when all of a sudden the car starts acting like it did before with the bad AFM. I check the code and now I get 31, no 24. Do I have a bad circuit? Car starts with AFM disconnected but now will not start at all with it connected (I get ignition then it dies almost instantly). Any help is appreciated.
 
Oct 11, 2005
3,814
13
38
Thousand Oaks, CA
Seems like it could be the wiring, probably at the AFM connector. Try wiggling and pushing on it while someone else cranks. You can use an ohmmeter to check continuity from AFM to ECU.
 

tomlson

New Member
Nov 2, 2017
3
0
0
Florida
My worry is that the new used part immediately got shot.. really making me want to go map. Wouldn't make sense for it to be a wiring problem if it just started working all of a sudden.

edit: I reset the ecu again and now I'm getting 51. Is this an ecu problem?
 
Last edited:

plaaya69

87T Supra
Nov 18, 2006
947
7
18
Lake County, IL
You did not try to clean the AFM did you? I have not seen a product for our type of AFM to clean it.

For me along time ago I got just the AFM electronics from a early 90's sc300 and it did not work for me. I don't know if it was just a bad sensor also but I found one from a turbo Supra and not had any problems since.
 

tomlson

New Member
Nov 2, 2017
3
0
0
Florida
You did not try to clean the AFM did you? I have not seen a product for our type of AFM to clean it.

For me along time ago I got just the AFM electronics from a early 90's sc300 and it did not work for me. I don't know if it was just a bad sensor also but I found one from a turbo Supra and not had any problems since.

I did not try to clean it. I got my replacement off a salvage 93 Sc. I will try to find a turbo Supra one. If anyone else has had a problems with an early 90s Lexus afm any help would be appreciated. Also any aftermarket AFMs people have experimented with.