I would have more confidence in your cleaning ability if you had numbers. Three months is not the number I'm talking about. If your adaptation numbers changed that would be significant. If you take a sensor running at 1.30 setting a code only when the conditions are right (wrong) and you change the adaptation to 1.29 and the condition is a little rarer I'm not sure I'd consider that much affect. Nor would I infer a three month delay much of a fix if it really did make a substantial change that went away that fast.

BTW, hot film air mass meters (which is what we are talking about) do not have a cleaning cycle. The hot wire sensors do.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician