Private wrote:

>
> I have a very similar problem as I posted last month. (post copied below)
>
> Mine is an OBD11 car with similar symptoms as yours. Shortly after my
> posting the SES light came on, so I did a scan which returned a code
> ISO9141, which nobody could identify??? On rescan I got a code PO147. I
> cleared the PCM and SES light did not reappear. It was suggested to me that
> I may have an IAC valve problem similar to yours and my reading and your
> timely post seem to confirm that this is the area needing further inspection
> and service.
>
> Did you attempt to clean the IAC valve or just replace it?
> Cost of new part?

I just replaced it. I got one at Car Quest for $50. It took about 30
minutes to remove the throttle body, replace the valve, and reinstall
it. Youtube has a good video on removing the throttle body on the
Saturn S series.

>
> The scan code ISO9141 was confusing but goggle returned
> http://www.obd-codes.com/faq/obd-ii-protocols.php
> I suspect this is important information when purchasing a code reader.
>
> My error searches found - P0147=Heated Oxygen Sensor HO2S Heater Circuit
> Malfunction (Bank 1 Sensor 3) M/T Only
> I do not understand what this may indicate? The only O2 sensor I am aware
> of is in the exhaust and it does not have a specific heater circuit. I had
> suspected that this may indicate faulty CTS? but now think it more likely
> that a malfunctioning IAC valve may be causing a false reading from the O2
> sensor. Why would this be 'M/T Only'?

It's always possible that there is more than one malfunction. The
overspeed 'sticky throttle' idle, though, is a dead giveaway for the IAC
valve if the throttle body butterfly valve is clean and working properly
since the only other way for air to get into the intake is through the
IAC port (assuming that there aren't any obvious vacuum leaks).



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