I thought the codes remained until reset by a scan tool; that is, even if the malfunction that caused the CEL corrected itself the code reader would show it. I may have been misinformed and I humbly bow to JimF's superior knowledge. I guess if I could choose anyone to catch my mistakes regarding CELs, JimF is the one I'd pick! Jim, your site is outstanding and I used it to learn a great deal about scan tools and MB electronics. In case anyone has not seen JimF's excellent site here is the link.
RIP "Betsy" (Oo=*=oO)
'96 E 3 2 0 (W 2 1 0) M 1 0 4 (Totalled)
Spaces in sig so as not to screw up the SEARCH; every time someone searches for that MB they don't want my sig!
2004 Audi A8L
'98 VW Passat 1.8T 5M
'87 Alfa Romeo Milano 2.5L 5M
'67 Impala convertible, 327cid