M said:
My battery was disconnected to do some maintenance, one of which was the
replacement of my SAS valve/air pump, which triggered the Check Engine
light. So far, the light hasn't come back on yet after 150 miles and a
week of driving. Is that sufficient mileage / car starts to be confident
that the Check Engine light won't come back on?
The air pump system is tested after the car is fully warmed up, when the
engine is at idle. This takes about 30 seconds of idling, during which
time the test is aborted or not started if the A/C comes on or is on.
The test is also aborted if you come off idle. So if you're in a warm
area where the A/C is always on, or not doing the type of driving where
you are sitting at idle for a period of time, then the test may not have
been run yet.
Note that it is only run once per trip, and 2? aborts will cancel any
attempts for the rest of that trip. Also, other systems are tested
during the above conditions, so this test doesn't happen every time.
Some OBD-II testers will also indicate "readiness codes" - once each
test is passed, the code for that test is changed from not ready to
ready. After a long battery disconnection, all of these are set to not
ready. This is how some jurisdictions test emissions through the OBD-II
port - all readiness codes must be set, and the check engine light off.
This is a bit of a snakebite, as people get check engine light problems
fixed, then get their emission check done - without allowing time for
the readiness codes to be set.
--
Mike F.
Thornhill (near Toronto), Ont.
Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)
