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Dan, Technician
Category: Saturn
Satisfied Customers: 24587
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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Over the course of the last year the service engine soon

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Over the course of the last year the service engine soon light has repeatedly come on throwing the code p0440. First it was the gas cap. Next, the fuel pressure sending unit. Then, it was the purge valve sensor. Now the same code and p1599 have been thrown together. My gas mileage has sucked for the last couple of years. I'm waiting on my mechanic to research what these two codes together could mean and to have some time to run some more detailed diagnostics on my Vue. In the meantime, I'm trying to research possibilities. The crankshaft position sensor was changed at my request last year. It's a 2003 4 cyl. Manual transmission with 210,000 miles. Engine was rebuilt at 180,000ish when I had clutch replaced. My suspicion is the fuel pump.
JA: How many miles are on the clutch? Has it been slipping or sticking?
Customer: Less than 30,000. No sticking. There's an occasional issue in 1st and reverse that I had prior to having the clutch replaced that never resolved. The feeling the the clutch is going out, but it's not. If I disengage the pedal and reengage, it's find. Doesn't do it for the mechanic. Can't figure it out.
JA: What is the model/year of your Saturn?
Customer: 2003 Vue 2.2 liter manual trans. Fwd
JA: Are you fixing your VUE yourself? What have you tried so far?
Customer: I have a shop I use. In addressing the p0440 code, we've addressed it diagnostically- the 1st time it was gas cap. The 2nd time it was fuel pressure sending unit. The 3rd time it was the purge valve sensor. Now we have 2 codes- the p0440 and p1599. I'm in a holding pattern. It seems the EVAP system is systematically failing.
JA: Anything else you want the mechanic to know before I connect you?
Customer: No

Hello, my name is ***** ***** I'm here to help get your problem solved.

Does vehicle ever stall at stops or seem to idle low?

Customer: replied 2 months ago.
No. That is what is really odd. The service engine light came on this past Monday while driving to work. After work I bee lined to the shop and on the way the light turned off. No code could be found. Then this morning the light came on again. Bee lined to shop and the two codes. My thought is fuel pump may be starting to fail only because these two codes due have that overlap. But, I'm not a mechanic :-)

fuel pump wouldn't cause p0440. 1599 means near stall condition happened, vehicle never stalls or seems to idle low?

Customer: replied 2 months ago.
No stalling or low idle. My idle is about 800/900 rpms

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.


  • he following are possible causes of a large leak:
    • The fuel cap is missing, is incorrectly installed or is leaking.
    • The EVAP vent solenoid is stuck open.
    • The EVAP purge solenoid is stuck closed or is blocked.
    • The EVAP vent hose is loose or is damaged.
    • The EVAP canister is leaking.
    • The fuel sender assembly O-ring is leaking.
    • The fuel tank or filler neck is leaking.
    • A condition may exist where a leak in the EVAP system only exists under a vacuum condition. By using the scan tool Purge/Seal function to create a vacuum, seal the system and observe the fuel tank pressure (FTP) parameter for vacuum decay, this type of leak may be detected.
Customer: replied 2 months ago.
My greatest complaint has been the drop in my fuel economy from 24/28 to 17/21 and a ping or knock, whatever term you want to use when I accelerate while driving. There are misfires, at least at idle, noticed today. And while I'm waiting for a time the shop that get the car in and hook her up and drive her around I'm looking for possible answers. It's the only vehicle I've got and don't want to be left on the side of the road if you know what I mean, lol.

Fuel pump would cause a problem under acceleration and not at idle. Does check engine light ever flash?

Customer: replied 2 months ago.
To detect those kind of leaks where does one go? A standard mechanic shop I'd assume isn't set up for that?

Most shops can do a smoke test, but any should be able to at least do a pressure test.

Customer: replied 2 months ago.
No. Haven't seen either service engine light soon or the service light with wrench ever flash.

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.

Customer: replied 2 months ago.
I appreciate the suggestions. I'd suggested recently when we replaced the purge valve solenoid to replace the black box with the canister just because of the mileage on the car and the fact the evap codes kept coming up and I'm a little tired of p0440.
Customer: replied 2 months ago.
Thank you.

No problem, let me know how it turns out or if you run into questions. You can reply to this answer at any time without additional fees, please do not forget to rate answer. Thanks.

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