2nd Gen R56 Cooper S Most liked posts in thread: How do Errors Reappear, After Time or Mileage?

It is not dependant on time or kilometers, if a sensor detects a reading out of specifications, the Engine Control Unit will set a code and cause the check engine light to turn on. If you delete the code with a code reader and the condition that caused the code still exists, the ECU will set the code again.

However, many times the conditions that would cause the ECU to set a code are transient or temporary, That means that the out of specification conditions lasted long enough to set a code and then went back to normal, in these cases you can clear the code and it won't come back.

if you don't delete these temporary codes, the ECU will delete them itself after a set number of starts I don't remember how many starts that it takes, it is something like 30 or 50 starts.

 

Some hard codes are stored on the ECU and you need a special tool ($287.00 Scanner) to clear them. I use the BavTech tool which you use with a laptop and the OBDII cable they send you.
http://www.bavariantechnic.com/buy.aspx

AutoZone, Wal-Mart and Pep boys scanners cannot clear the hard codes saved in the Eprom.

 

+1 to the above....
On so e items the computer just reports what it sees....some items have a test procedure that the car monitors, or a cycle....the emissions systems usually use a combination of running conditions (hot, cold, open loop, closed loop etc) before it flags an error...but it usually has a "readiness" monitor that monitors the system and flags it as not yet passed or ok'd yet and this might not be eligible to pass an inspection if you have one for that system....

 

What kind of error code are you getting genik?

 

Oops

 

What code did you get?

 

Go get the code and report back.

 

Hmm. Pencil and paper works wonders.

 

So no info means no help. :lol:

 

The cat efficiency code will likely reappear in a few days after the "cycle".... it basicly means your catalytic converter is no longer working....often due to age or leaded fuels....sometimes a leak or bad flex joint can be the issues...letting in o2...the oxygen sensor just sees excess o2 and says it's not working. So do check for exhaust leaks....like a cracked header pipe, bad flex joint, or bad gasket.
Power train is just a generic code.... sometimes from wheel spin...not super common on gen2 cars, it is VERY common on the gen3.