Check Engine Light from Hell

[lc9063]

I am at my wits end in MD!!!Beginning in early April, my check engine light went on and has barely gone off since.First they replaced the vent control valve ($$) with kept the light off for 2 days.Then they replaced the PCM. A short was noted.Light comes back on.Then they (diff. dealer) replace missing hose from throttle body to evap purge (Code P0446)Light comes back on.They then replace the Oxygen sensoe (Sensor 3.682??)Light comes back on.Has anyone come accross a similar situation?I was looking forward to getting a new AWD vibe sometime in the future. NOT ANYMORE.Sincerely,

[ToolGuy]

Doh! To me it sounds like each dealer is resetting the computer, which turns the light off and throwing parts on it to fix it. When that does not work the light comes back on. I would try to find a local auto store that will read the code for free for you.Write it down and we can look it up for you and go from there before you spend more money on it.

[engineertwin2]

^ What he said. Do you have a list of the codes? The dealer should be able to provide that information for you (it should've been on the paper work).What reasoning did they give to replace an O2 sensor? If they felt the need to replace an O2 sensor, it could've been the Catalytic Converter. How many miles are on your car?

[lc9063]

The only code I code find on any of the invoices was the one above (P0446). I currently have a little under 44k miles on the vehicle and have had it since Jan 2004. I was suprised they needed to change the Spark plugs so soon. The invoice says, "plugs were gas fouled out from H2O sensors". A note under the PCM replacement notes, "shields on input wires were grouded out".It hesitates a bit when I give step on the gas. It's sorta hard to describe, it just "feels" different. Almost like it's taking its time to accelerate compared to what it was before. Although, the RPM at higher speeds (65-85 MPH) appears unchanged. In a little while I'll be leaving to drive up to NY, about 200 miles, so hopefully it wont self destruct.Best Regards,

[ToolGuy]

P0446 is an EVAP Evaporative Emissions Code and here is what the GM manual states. When running the DTC P0446 Evaporative Emission (EVAP) Vent System Performance diagnostic, the powertrain control module (PCM ), monitors the fuel tank pressure (FTP) sensor. When vapor pressure rises to a specified value, the PCM commands the vent valve open, and monitors the FTP sensor signal. Pressure will increase rapidly because of the air allowed into the system. No increase or an increase below a specified rate indicates a restriction on the air inlet side. The PCM then commands the pressure switching solenoid closed. This blocks air from entering the tank side of the system. The PCM monitors the fuel tank pressure FTP sensor and looks for a decrease in the pressure rise. If there is no change in pressure the PCM concludes the pressure switching solenoid did not close. If the PCM does not detect an increase in pressure, or the rise in pressure does not change, a DTC P0446 will set.It also states this for diagnostic aids:If DTC P0446 is the only EVAP DTC set, the most likely cause is an inoperable EVAP canister vent solenoid, or pressure switching solenoid. Inspect the EVAP solenoids carefully for faulty connections and erratic operation. • If the DTC cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was first set. • Operating the vehicle in Check Mode will increase the ability of the powertrain control (PCM) module to detect engine control system malfunctions. Refer to Check Mode in Service Bay Test . • An intermittent malfunction may be caused by a fault in any of the EVAP solenoid electrical circuits. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions . This codes seems to call for a lot of diagnosis with it since there are 29 steps also listed in the manual for diagnosis. However this is only telling me what code was listed but not the current code if the light is still coming on. It may be the same code but again for a correct diagnosis the code should be read again or when the light comes back on. You can also search this site under P0446 and see if someone else has had the same code and what was fixed on theirs. It really sounds like to me someone is just really not spending the time needed to fix this for you correctly. Secondly all the dealers work is guarenteed so I would go back and say the light is on again and if you can have an auto store tell you the code you can then tell the dealer it is the same code YOU told me was the issue thus you did not fix the issue the first time.Lastly, every GM dealer has a tool we sold them called a Vehicle Data Recorder part number J-42598-B. It is a device with a button, sits in a cup holder and plugs into the Diagnostic Port inside the car. It is made to be connected to the vehicle and let the customer take it to use. It works simply by when the vehicle acts up or a light comes on, the customer quickly pushes the large button on the top of the tool. The tool then takes a snap shot of exactly what the vehicle is doing at that point in time. The dealer then downloads the info and can analyze it. You may want to ask the dealer about using this tool...

[Mojo72]

Before buying my '04 Vibe, I was warned by the seller of an intermittant check engine light. My independent mechanic ran a diagnostic test and came to what I remember to be roughly the same conclusion as yours. After asking him if it was worth pursuing a repair, he said that such hairline leaks are very difficult to locate and that I could live with the check engine light. Since approximately 5 tank fill-ups ago, the check engine light has been steady on, but I've been averaging approximately 28.5 mpg in normal commuter driving. If my fuel mileage hasn't suffered, should I still seriously consider addressing the check engine light with a diagnostic and repair?

[moongdss]

Heya, I'm over in Laurel and if you need, we can meet up and plug my scangauge into your Vibe and read the trouble codes. You can then search online (or here!) for the meanings of the codes. I agree with ToolGuy, ask the dealer for that nifty tool! Have you dealt with the Laurel GM on Route 1 at all? Which dealerships have you gone in for work (if you don't mind my asking) and what was your opinion of them?Cheers!~Diana

[NibCrom]

You MAY want to get GM customer service involved. I had the same sort problem with my Olds Alero. Check engine light would go on and off all the time and the dealer "repaired" in under warranty like 6 or 7 times. Something to consider if other options fail. I'm not sure what the 800 number is, but it's probably in your owners manual.