As for the air flow fault, thing one maybe as the result of the carbon build up within the heads.Ridgeback_Pilot said:Friends: My car is a 2000 Dinan M5. Lately I've been getting the SES light on long drives. It usually takes about half an hour to come on. The codes are always the same (Table 18):
AA: "Secondary air system, flow too low"
AE: "Air-fuel adaptation, Cyl #1-4"
AF: "Air-fuel adaptation, Cyl #5-8"
Anyone care to hazard a guess what this means? I realize the secondary air system is a mechanism to help the cats warm up faster, which isn't really necessary in the benign climate of northern California. But what about the "air-fuel adaptation" codes?
Does this affect performance at all?shadowman said:As for the air flow fault, thing one maybe as the result of the carbon build up within the heads.
If the faults are 80 and or 81 then in all likelihood you are dealing with the following;
BMW has a lengthy test however you can do a baseline test for this by removing the primary O2’s and then activate the secondary air pump and feel for good air flow. Good air flow will be similar to a hair dryer strong. If this test fails then the BMW recommended fix is to pull the heads to have the carbon build up removed….
FYI, BMW posses this as a possible concern after 35000 miles….
lwebb12 said:Does this affect performance at all?
I get these same codes all the time but the pump seems to work fine.
Do the passages for the air become blocked in the heads or is it the pump itself that gets clogged?shadowman said:Mechanically speaking no, however because of the SES light and the fact that this triggers an OBD2 failure (smog) in the states that require a smog check it will not pass.
You are correct, the pump typically does work fine but what is happening is the circulation is hampered and in all likelihood will eventually become completely blocked.
Otherwise, you are good to go.