Saturn Repair Problems? Ask a Mechanic for Answers ASAP
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Does vehicle ever stall at stops or seem to idle low?
fuel pump wouldn't cause p0440. 1599 means near stall condition happened, vehicle never stalls or seems to idle low?
Well the P1599 usually means the throttle body is dirty so I'd start by cleaning that, I think idle is probably going low even if you aren't noticing it otherwise code wouldn't set. P0440 means evap system is leaking, since everything has pretty much been replaced it sounds like your fuel tank pressure sensor may be failing, this is what detects if there is actually a leak. I would recommend having a pressure test done on fuel tank, if it doesn't hold pressure then do a smoke test to see where leak is. If it does hold pressure then replace the pressure sensor. Here is a list of possible causes from manual. Let me know if you have questions, thanks.
Fuel pump would cause a problem under acceleration and not at idle. Does check engine light ever flash?
Most shops can do a smoke test, but any should be able to at least do a pressure test.
The evap leak is only emission related though and is not the cause of vehicle idling rough or ping/knock. I would start by cleaning throttle body, this is common to cause a rough idle and can cause airflow restrictions which can make it ping/knock while driving. I think that will at lest help the idle problem if it still seems to have issues while driving I'd replace the spark plugs. Let me know if you have quwestions, thanks.
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