[Joshboody]

Do stored codes have a lifetime?

Had some cold start misfires recently in the past month which were stored as codes, read by the BT tool. Wasn't a big issue to me so I waited to visit dealer. Checked that they were still there about 2wks ago, but then again took my time visiting the dealer. Finally dropped off the car and explained the situation, but when diagnosing they found no codes and no issues. I will check again with BT tool once get car back tomorrow.

FYI: had plugs and injectors changed on bank 2 before, but engine malfunction remained on... but same codes this time on bank 1.

just curious if codes can disappear... Thanks

[twinship]

Originally Posted by Joshboody

Do stored codes have a lifetime?

Had some cold start misfires recently in the past month which were stored as codes, read by the BT tool. Wasn't a big issue to me so I waited to visit dealer. Checked that they were still there about 2wks ago, but then again took my time visiting the dealer. Finally dropped off the car and explained the situation, but when diagnosing they found no codes and no issues. I will check again with BT tool once get car back tomorrow.

FYI: had plugs and injectors changed on bank 2 before, but engine malfunction remained on... but same codes this time on bank 1.

just curious if codes can disappear... Thanks

Curious about this as well... anybody know?

[I335]

Good question - I always wondered about this too. Perhaps they just eventually get overwritten?????

[roadkillrob]

There may be some type of a counter, like 10 cold starts without a misfire and it will clear the code, other codes work that way and go away after x number of good cycles.

[dmurray14]

OK - I'll shed a little info on this but not too much. The ECU has two "code banks." Codes start out in the one bank, and that's where you saw them the first time. After a while, they expire and are stored in a history bank. At this point they wouldn't show up as normal ECU error codes. It's likely that your code expired and went into the history bank.

[Bimmer This]

I always though that it was 100 ignition cycles without any current trouble codes.

[Joshboody]

thanks for the info... makes sense. I am curious whether BT still shows the codes, and i'll check later. I would suspect that maybe once the SES light disappears the codes are stored as history.

[scalbert]

Originally Posted by dmurray14

OK - I'll shed a little info on this but not too much. The ECU has two "code banks." Codes start out in the one bank, and that's where you saw them the first time. After a while, they expire and are stored in a history bank. At this point they wouldn't show up as normal ECU error codes. It's likely that your code expired and went into the history bank.

Bingo, different codes may require different warm up cycles, and the problem is no longer present, to when the SES is turned off. But they never disappear until cleared.

[dmurray14]

Originally Posted by scalbert

Bingo, different codes may require different warm up cycles, and the problem is no longer present, to when the SES is turned off. But they never disappear until cleared.

Well, there's actually more than that -- the ECU actually keeps two separate error logs within itself. I'm assuming we're talking about BMW-specific error codes in the ECU, not OBDII codes (which, as you say, require x warmup cycles to clear). But yep, similar concept.

[bulldog_yyc]

Originally Posted by dmurray14

Well, there's actually more than that -- the ECU actually keeps two separate error logs within itself. I'm assuming we're talking about BMW-specific error codes in the ECU, not OBDII codes (which, as you say, require x warmup cycles to clear). But yep, similar concept.

and are you suggesting that the BT cable cannot access this second memory bank?

[Joshboody]

checked with BT, and my codes did disappear.

[dmurray14]

Originally Posted by turkish335

and are you suggesting that the BT cable cannot access this second memory bank?

No, I'm not suggesting that. I'm just shedding some light on how the codes are stored.

[bulldog_yyc]

Originally Posted by dmurray14

No, I'm not suggesting that. I'm just shedding some light on how the codes are stored.

[Alan l.]

Strange thing for me is that i keep getting the same codes even after clearing it with the Bt scanner when i took my overhead map light cluster off to hardwire my V1. it caused some faults because the car thought something was wrong with the SOS button since it was unplugged. I would reset it with the BT tool....and it would go away for awhile but it would come back. Everything was plugged back in and works perfectly so i have no clue why the same codes keep popping back up.

[shifterboy45]

Originally Posted by Alan l.

Strange thing for me is that i keep getting the same codes even after clearing it with the Bt scanner when i took my overhead map light cluster off to hardwire my V1. it caused some faults because the car thought something was wrong with the SOS button since it was unplugged. I would reset it with the BT tool....and it would go away for awhile but it would come back. Everything was plugged back in and works perfectly so i have no clue why the same codes keep popping back up.

i think there is a difference between "check control" messages (like a failed light bulbs or systemic issues) and DME fault codes..

i do believe they have different life-cycles..

[dmurray14]

Originally Posted by Alan l.

Strange thing for me is that i keep getting the same codes even after clearing it with the Bt scanner when i took my overhead map light cluster off to hardwire my V1. it caused some faults because the car thought something was wrong with the SOS button since it was unplugged. I would reset it with the BT tool....and it would go away for awhile but it would come back. Everything was plugged back in and works perfectly so i have no clue why the same codes keep popping back up.

Chances are there's still a fault then. I'd double check to make sure. Does the BT tool show the fault currently being present?

Maybe some wires are loose? Can't hurt to re-check.