snap-on

If you added more than 5 gallons the car will run a Evap test on the next vehicle shut down.
Your vehicle runs the Evap test after you park it. This is a departure from pre-2003 Mazda vehicles that use engine vacuum to test the car as it is running.

velocityredRX-8

I had one in my car for them to use, but all that they told me was that they needed to use the factory one. Thats such BS because the representative told me that the evap system was the problem before they even diagnosed the car. I dont understand why they just cant perform what is needed. Now I have to drive 45 mins to another dealership and I dont even know if they will give me a car to use for the meantime.

brtzrx8

Call ahead and ask if the dealer will give you a car. I check with a number of dealers here in the Bay Area and have not had an issue with the loaner car.

They need to communicate with the PCM as part of the service as well. I wonder if they are having problems communicating with that. I had a blown fuse which was an issue. This seems to be a good article explaining all this.

http://www.aeswave.com/images/Produc...6%20sample.pdf

Good luck... ...

brtzrx8

This is interesting. Are you saying that EVAP tests are conducted when your car is not running and parked?

This is consistent with how my CELs occured. Always after I parked it for sometime and restart.

One thing though, if you clear the code manually, the system will try to complete a EVAP retest. I wonder if my refueling the car before this was complete, triggered the pending code... ...

Oh well, I'll drop by the dealer tomorrow and chat with the tech.

snap-on

Thats is exactly what I am saying.

The "pressure based evap" (PBE) tests the system after the car is shut off. I'll copy and past this info from mazda6tech.com. I did this write up a couple of years ago.

Notes by Snap-On:
When the OBD II mandates hit the manufactures in the mid-ninties one of the monitored functions was to check the integrity of the "evaporative emission control system". The check is based on the theory that many cars where letting fuel evaporate due to loose or missing fuel caps, and the evaporating fuel was damaging the ozone layer.

Since 1994 most manufacturers have used the VBE or "vacuum based evap" check that requires the vehicle to be at normal operating temp and the car be in"cruise mode". This systems parameters caused a concern with the EPA. Some cars never get full warm up and some cars never get to "cruise mode". VBE used vacuum, which is a by-product of gasoline engines. After the vehicle parameters are met (if ever) the the PCM commands a valve to open and allow the fuel tank to evacuated. A sensor in the tank picks up the vacuum signal and the PCM sets an internal timer. When the PCM re-checks the sensor after a given amount of time and the vacuum is gone the system flags a loose gas cap code PO442/456 for a small leak or a PO455 for a large leak.

Now for the latest and greatest.

Mazda has been tasked from the Ford family to pioneer the PBE or "Pressure Based Evap" system.The newest requirement is to monitor leaks smaller than .020 inch. The system is a self contained system first used on the 02 MPV but used on every Mz6. A Small(6"x6") module is mounted near the fuel tank of the vehicle. Each module contains a small pump and a COV(Change over valve). The COV is a three way valve. Position 1) is vented to atmosphere. Position 2) is a .020 orifice. Position 3)is to the fuel tank.

Once the owner adds or uses 5 gallons of fuel and the vehicle is shut off the PCM commands the pump to run. the PCM monitors the amperage in the circuit and take this as a "base line" reading. The PCM them commands the COV to move to the .020 orifice position and the amperage in the system is evaluated and the two readings are stored. The COV is then commanded to send pressure to the fuel tank..the Pcm then times how long it takes to go from the "no load " reading to the "full load" reading (.020) and if the specified time is exceeded a code is set.

brtzrx8

Brought my car to the dealer today. They told me that the codes were not cleared during the last service. That is supposedly the reason for the pending P0455 code. The tech believes that to be the case as there were some uncleared U codes as well.

Note sure what U codes are. In any case the car still needs to complete the EVAP test. Hope it doesn't throw any codes in the process. Everything seems to be working fine now.

zoom44

yes yes yes- if something happens which causes the test cycle to be interuppted/not complete it will throw a code.

when the cars first hit the ground with K flash there was a bug int he software. if youoperated the key fob to to lock/unlock the doors etc just as the test was starting to run it would interupt the cycle and you would get a evap test failure code. this was intially thought to be a lot of loose gas caps until the issue was found and fixed with L flash.

of course we have sen a few leaky caps since then as well. but if your scanning device can prompt teh evap test to run then lat it run all the way thru.

snap-on

"U" codes represent a break in communication on the CAN bus. Anytime the IDS/PDS is connected to the vehicle this is a possibility for them to store. The laptop basically tries to add itself to the LAN in the car.

Mazda has actually engineered the software to automatically clear the U-Codes after every reflash. When a flash is directed to a particular module the other modules are ignored and "U" codes are set.

zoom44

U codes sometimes pop up after using a can scan device. i have seen it early on with the harrison model but i think that was fixed. havent seen it with Hymee Scanalyser at all. have heard of it but not seen it personally with other models

brtzrx8

The saga continues. MY CEL came on again last week, same code P0455. I brought it into the dealer. The root caused it to a EVAP solenoid and replaced it. I took the car back drove 75 miles and the CEL came on again.

My car is back at the dealer for the 4th time today. I'll have to see what they find this time. At this point, I am starting to smell a lemon. This really sucks... ....

I am wondering if my audio install has anything to do with this. I used the some factory ground points. Wonder if it is interfering with the EVAP system.

Hey VelocityRed, any news from your end?

velocityredRX-8

I just got back from a trip and haven't had time to take my car to another dealership. I'm aiming to take my car to the dealership this week. I'll let you know what happens.

brtzrx8

Just got my car back, and it turns out that a screw used to mount my subwoofer had punctured a charcoal canister in the EVAP system. This obviously is not covered by the warranty, and I had to pay for both parts and labor.

I am out $1100, but I guess my CEL issue is finally fixed. This really sucks, but I guess it could be worse.

I'll post some pictures on the audio section to help others avoid this.

snap-on

Ouch

velocityredRX-8

That really sucks.