Active vs. and Inactive code

[HSLD]

What's the real difference between an active and an inactive fault code?

v/r

HSLD

[LSMR]

A active code is a problem that you are having right now.Could be a faulty sensor ect. Usually an active code will set off the check engine light.

A inactive code is a problem that has happened but may have been a momentary fault that corrected itself.A good example is this-many Detroit 60 series will show a code for low or no oil pressure.The reason for this code is because when the truck was serviced the filters were probably installed dry.When the engine was started it took longer than normal for the computer to sense oil pressure.After oil pressure was sensed this condition was resolved.Although no check engine light came on the code is stored.

Inactive codes can be used by a good tech to determine intermittent problems.

[HSLD]

A active code is a problem that you are having right now.Could be a faulty sensor ect. Usually an active code will set off the check engine light.

A inactive code is a problem that has happened but may have been a momentary fault that corrected itself.A good example is this-many Detroit 60 series will show a code for low or no oil pressure.The reason for this code is because when the truck was serviced the filters were probably installed dry.When the engine was started it took longer than normal for the computer to sense oil pressure.After oil pressure was sensed this condition was resolved.Although no check engine light came on the code is stored.

Inactive codes can be used by a good tech to determine intermittent problems.

Ok, that makes sense. I've got an inactive code for accelerator postion low voltage. I've had a check engine light on and off for some time now. I had it in the shop and they didn't find any codes or any problems. Today, when I hooked my PDA up to the truck I got a inactive fault code. I got the check engine light for the first time in a few months again on the last trip. So, I'm replacing the position sensor for the accelerator in the morning.

v/r

HSLD

[LSMR]

Two things I forgot to mention:

1) Before you replace any componets clear all your active & inactive codes.After you do this take the truck for a run and recheck the codes.Sometimes previous repairs may have been done and the tech who did them didn't clear the codes.

2)If you want to do your own repairs invest in factory service manuals.They will save you a lot of time & aggravation.

[HSLD]

Two things I forgot to mention:

1) Before you replace any componets clear all your active & inactive codes.After you do this take the truck for a run and recheck the codes.Sometimes previous repairs may have been done and the tech who did them didn't clear the codes.

2)If you want to do your own repairs invest in factory service manuals.They will save you a lot of time & aggravation.

The problem seems to be the accererator position sensor. The instructions said to take care of all other fault codes before replacing the sensor, becuase the sensor replacement resets all codes upon starting the truck.

I replaced the sensor this am, it was old. So i'm thinking I'm on the right track. Hope so.

I did buy the manuals, but the section on codes left me scratching my head a little. In other words, I thought I understood things, but wasn't quite sure. What I take inactive to mean, and what it really means seem to be a little different. Then after talking to FW Freightliner, and buying the new sensor, I decided their idea of an inactive code was even different than mine or the manuals.

v/r

HSLD

[Capt._Chaos]

It's important to be sure those codes are cleared out once the problem has been corrected.

Some of those active codes will de-rate the engine output to help keep the engine from self-destructing until they are removed. Others (particularly with some Cummins electronically-controlled engines) are set in the ECM to limit road speed to around 35-40 MPH until cleared (like a "limp-home" mode).

[HSLD]

It's important to be sure those codes are cleared out once the problem has been corrected.

Some of those active codes will de-rate the engine output to help keep the engine from self-destructing until they are removed. Others (particularly with some Cummins electronically-controlled engines) are set in the ECM to limit road speed to around 35-40 MPH until cleared (like a "limp-home" mode).

If you remember, I've been having the check engine light for sometime now, on and off. I've had it in the shop and was always told there were no codes and they couldn't find anything (two different shops). The light always seemed to be on rainy, wet days or high humidity days. So, I got to thinking that was it. And when I posted it here, other's kind of thought that might be it as well.

Then, I buy Detroit's Pocket Diagnostic Link and find an inactive fault code. It was for accelerator position low voltage. I go by FW Freightliner, get the new sensor and talk to the service dept.

Installed the new sensor and wiring harness yesterday. Of course the installation cleared the code, but we'll see if that fixed my problem.

v/r

HSLD

[HSLD]

2)If you want to do your own repairs invest in factory service manuals.They will save you a lot of time & aggravation.

I'm really not wanting to do my own repairs. But, most of the repair shops here locally that I'll use are swamped right now. Something as simple as this sensor replacement, I could have lost two days (or more on) waiting for "my turn" at the shop.

So, if it's as simple as this sensor I just replaced, I can see doing that. It was a straight forwrd 30 minutes job. And I keep my "laundry list" of things I want and need done for when I take vacation and can leave the truck in the shop for a week.

v/r

HSLD