Robert said:
In the interest of keeping this thread going...
I keep getting the SAS Malfunction code as well, but I can't bring myself to
replace the $300 blower for the following reasons:
1) The light never comes on at startup or during the first two minutes of
driving. It usually comes on after the car is warm and has been running for
15-20 minutes. I'm under the impression that the SAS pump only runs for two
minutes at startup, so why would it kick off a code so much later?
2) I can feel/hear the pump running for the first couple of minutes after
startup so I know the motor's not burned out.
3) The light only comes on once a week or so, not every time, so I know the
motor's not burned out.
So perhaps I have a wiring problem that occasionally wiggles itself to
simulate a fault?
Can anyone tell me what exactly triggers the fault, i.e. what electrical
signal indicates a fault? Is it the current draw on the SAS pump motor? Is
it the O2 sensor level at startup?
My Haynes manual only dedicates one sentence to the SAS system,
acknowledging its existence, and it doesn't appear on the schematics.
Thanks,
-RL
The computer has no reliable way of sensing if the air pump is working
at cold start. So, it's tested after the car is warmed up. When you
come to idle, sometime after the car is warmed up, the computer stops
adjusting the mixture and monitors the front oxygen sensor, then turns
on the air pump system. If the oxygen sensor does not report more
oxygen in the exhaust within a few seconds, then it believes there's a
problem with the air pump system.
These test conditions may not occur in every trip you take, and if the
A/C comes on, or the throttle goes off idle, the test is aborted. 2
aborts and the computer won't try to retest until after the next cold
start.
If your pump is running, chances are it doesn't need to be changed, no
matter how noisy it is. In addition, there is a solenoid valve that
needs to open to allow engine vacuum to open the SAS valve. And of
course the purple vacuum hose between the solenoid and SAS valve has to
be OK. The wires can come off the solenoid valve, something can go
wrong with the vacuum supply, and the SAS valve can be seized closed.
On my '98 V70 the pump has been noisy for more than a year, and still
works fine. The SAS valve would not fully close, so I changed that last
year when I first noticed the pump noise. On my '98 S70, the pump was
dead (burned out motor, seized shaft) when I bought it in '02. Also the
SAS valve was seized closed. A friend with a '98 V70 had a noisy pump
in the fall, I counselled him to ignore it after letting him hear mine,
but his was dead within 2 weeks.
--
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.)
