The yellow light comes on and stays on (no flashing). Took it to one mechanic and he said I probably had the cap not on tight enough (but I am always carefully to listen for three clicks) . He reset it so the light went off. A week later the light came back on. Took it another mechanic. The code was still gas cap so he put on a new cap (said it would be $15 but afterwards said it was $30, so $30 down the drain since two weeks later, the yellow light is back on again. There are no symptoms that anything is wrong with the car and I doubt this is going to be anything other than the same gas cap code the third time, but I am not really into putting black tape over the light and pretending it's not there. Help please !!!
Get gas cap from dealer as some vehicles are having issues with the after market caps. What is the actual code and what's the vehicle year, make and model?
Testimonial: "Good information but my problem went away for now so I really need for the light to come back on before I can know if there is still something wrong. According to the operator's manual, that light can come on (if not flashing) for many reasons that might be temporary."
Not sure about the price at dealer. Since you have already paid to have your vehicle diagnosed and the issue was not addressed you should by all means take it back and have it diagnosed at no further charge you may have to pay for the repair though. I was wondering why you didn't do that the first time rather than taking it to a different mechanic. Also you could go to autozone and have the code scanned for free that way you have more info and it may help help you.
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First of all, it does absolutely no good to clear codes without properly diagnosing the code and correcting the problem that caused the code to set in the first place. It will only result in the code returning again and again as you can now see.
You must also know how the system works and what failure is indicated by the code. Please note that fault codes NEVER tell you what parts to replace. Then you must know what conditions in the system cause the code to set in order to perform a valid diagnosis of the system.
failure.
With all that said, let's take a look at the code itself:
Diagnostic Test Code (DTC) P0496 is defined by SAE J2011 as "Evaporative Emission System High Purge Flow".
Purge flow is determined by the Powertrain Control Module (PCM) by looking at the Fuel Tank Pressure (FTP) sensor. When there is little or no purge flow, the FTP sensor will read high pressure. If there is too much purge flow, the FTP will read low pressure.
The code is clearly stating that there is too much purge flow (or low pressure/high vacuum in the tank). The people that have been trying to diagnose this problem apparently do not understand this. Leaks in the system like leaking lines or defective fuel caps will cause the pressure to be too high when it is SUPPOSED to be low and will set a code P0455, P0456, or P0457. Smoke testing and fuel cap replacement is what you do for THESE codes, NOT code P0496.
In simple terms, what is happening here is that the PCM is telling the EVAP system to stop purging and it is continuing to purge anyway. This is usually caused by a stuck open Purge Control Solenoid Valve (PCSV). Now I do not know which solenoid they replaced, but I am willing to bet that they replaced the Canister Control Valve (CCV) also known as the "vent solenoid". Again, this might be a good strategy for the other codes listed above, but not the code we are working with.
The other thing that eats at my craw here is that they are randomly replacing parts, evidently without testing them first to see if they are defective and/or are the CAUSE of your problem. I do not call this diagnosis. I call this "parts-nosis". This is where a technician just starts replacing all the parts in the system untill he finally finds the one that takes care of the problem. And YOU have to pay for it! Not only are you paying for parts that do not fix the problem, but they also have the nerve to charge you for "diagnosis" time to find the problem. Then they wonder why people think that mechanics are nothing but a bunch of rip-offs!
So plain and simple, they are not finding anything wrong with your EVAP system because they are simply looking for the wrong problem. They are looking for a system leak when they should be looking at why the pressure is low or vacuum keeps increasing when the PCM is telling it to stop.
There is pretty much only three things that can cause this code:
> Stuck open PCSV (most likely)
> Defective fuel tank pressure sensor
> Defective or mis-calibrated PCM
SOURCE: I had a mechanic test
This indicates that a part of the EVAP control system is no longer fuctioning correctly. The EVAP system consists of many parts, including (but not limited to) the gas cap, fuel lines, carbon canister, purge valve, and other hoses. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.
EVAP emission canister purge is contolled by a valve which allows engine vacuum to pull stored fuel vapors from fuel tank into the engine to be burned, rather than be vented to atmosphere. A vacuum switch is used to detect when flow exists. If the PCM commands purge and sees that the switch is closed (indicating no detected purge flow) P0441 is set.
Symptoms: Likely, no symptoms will be discernible to the driver, other than the illuminated Check Engine Light.
Causes: A code P0441 could mean one or more of the following has happened:
* Bad vacuum switch
* Broken or damaged EVAP line or canister
* Open in PCM purge command circuit
* Open or short in Voltage feed circuit to Purge Solenoid
* Faulty purge solenoid
* Restriction in EVAP solenoid, line or canister
* Corrosion or resistance in purge connector
* Bad PCM
Possible Solutions: With a P0441 OBD-II trouble code, diagnosis can be tricky at times. Here are some things to try:
* Common Chrysler fix - Replace Leak Detection Pump / LDP
* Repair damaged EVAP lines or canister
* Repair open or short in voltage feed circuit to Purge Solenoid
* Repair open in PCM purge command circuit
* Replace purge Solenoid
* Replace vacuum switch
* Repair restriction in Evap line or canister or soleniod
* Repair resistance in purge connector
* Replace PCM
Hope this helps.
SOURCE: Service engine light keeps coming on
need to scan for codes and find problem code some part stores do for free
The information below was complied by me, it explains what causes the check engine light to come on and the process of finding the cause.
When the yellow Check Engine light (or Service Engine Soon) is turned on, the systems computer control unit (called the PCM) has sensed a fault in the electronic controls of the engine and/or the emission system. When this happens you will seldom feel the car engine run any different. There are about 200 possible system faults (the gas cap is just one of them) that turn the Check Engine light on, to know what has developed a problem you must have the system tested, this is called an OBD2 fault code test, Kragen/Oriley and Autozone parts stores (USA only) do this testing for free.
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2001 Grand Am SE V6. I don't know the exact code. Should I complain to the previous mechanic about the gas cap or just swallow the loss (I was grossly overcharged for the cap after checking the price lists at parts stores ($15 instead of $30) but let them go ahead and put it on because they said there was some installation 'ointment' that is applied with a new cap (which I guess is just glorified vasoline) and I didn't want to take any chances on more annoying trouble with this issue, so I'm pretty ********** to pay that much and find out the cap is no good. How much is one from a dealer...not more than $30 I hope.
Thanks for your reply.
First, as far as goes aftermarket quality, I usually find the aftermarket products better quality or at least as good (the respectable brands, that is), so that is helpful information, but I am not too comfortable buying yet another gas cap on the odd chance that that is the problem, especially since I can't be sure for a week or so if the problem is solved because when the car's computer is reset, it is about a week before the light comes on again. Does that sound more or less like a bad cap?
Second, the reason I didn't go back to the first mechanic is that he is really, really good and also honest and charges fair rates...which unfortunately means that getting to see him can take one to two weeks. Mr. Transmission read the code for free and I asked to buy the cap from them when told it would be $10-15, when he up the price, I should have just said "put the old cap back on", but I don't like doing that kind off thing over relatively small amounts of money. Thanks again.
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