Can historical codes cause problems?
Thread Starter
Safety Car
Joined: Nov 2003
Posts: 4,323
Likes: 0
From: MA
Can historical codes cause problems?
OK here is the situation. About a month ago on my way to work my car continuously would go into reduced power mode. Always fun on a major highway. Current codes came up as the throttle position sensor. So I replaced this. Everything seemed fine until yesterday I got reduced engine power twice on the way home. Codes came up as the same codes from before but were historical. Both times I cleared the codes and when I got home I disconnected the battery. I didn't drive the car today but I was wondering why would these codes come back as historical if they were cleared? Why wouldn't they come up as current if they were actually causing the problem? Thanks
Safety Car
Joined: Apr 2004
Posts: 3,738
Likes: 10
From: Austin, Texas
That does seem 
But I doubt that codes can actually cause problems to occur. They are the result, or log, of actual problems.
I don't know anything about the code in the PCM, but I guess it is possible for the software to "remember" that these are the same codes as before and log them as H instead of C.
Wouldn't be the best way to code it, IMHO, but it might explain this situaton.
It is a PITA because until you get a "current" code, you won't know whether or not the position censor fixed (or did not fix) the orginal problem. My guess is that it didn't, based on how the car is acting.
Hopefully, there is someone out there that knows how the code is written, or has experienced a similar problem.
Good Luck,
But I doubt that codes can actually cause problems to occur. They are the result, or log, of actual problems.I don't know anything about the code in the PCM, but I guess it is possible for the software to "remember" that these are the same codes as before and log them as H instead of C.
Wouldn't be the best way to code it, IMHO, but it might explain this situaton.
It is a PITA because until you get a "current" code, you won't know whether or not the position censor fixed (or did not fix) the orginal problem. My guess is that it didn't, based on how the car is acting.
Hopefully, there is someone out there that knows how the code is written, or has experienced a similar problem.
Good Luck,
