Hi All
2002 Mazda 626 LX 2.0 throwing P0442 and P0455 evap leak codes. Cleaned filler neck and new cap. New purge valve. Vent valve is KLG4-18-741 and is tough to find and expensive (150 USD). Working on that. Also, the tank pressure sensor appears to be separate from the fuel pump and tough to determine the OEM number (KG-G0070AN? possibly). Would love for a knowledgeable person to help identify the pressure sensor part number and location in the system. Smoke test did not reveal a leak, so I imagine it is component failure. Vent solenoid and pressure sensor are the only other moving parts (besides the cap and purge valve already replaced that were easy and cheap). Any better approaches welcome. Pics and diagrams very welcome and appreciated too. Thanks in advance..... -Rich

 

Welcome to the forum
Rule of thumb that is often not followed by DIY is verify a part as failing or failed before randomly replacing them. If you did your research, there is an exact problem tree solving procedure based on thos DTC you posted and you skipped a few of them.
As for the OEM part number I suggest contacting your local Mazda dealership dire as internet information on correct oem part numbers can vary and there may be NOTES: to read about the part as well other important question that a simple look up a part number by anyone but you or a Mazda dealership can answer or ask you specifically about you Mazda.

Some examples but may not be all pertaining to any particular OEM part number that only you could answer but not all other variables having to do with getting the correct OEM parts numbers and part.

Model Production date (look at tag in your drivers door jam)
VIN or specific VIN numbers (the sub notes in the part number listing will specify )
Federally of California emissions (will be a decal/sticker under and on the hood)

 

Thank you for the response. The car evap system is original and the car is in great condition and runs well. I would rather throw a few bucks (appx $200) to replace all of the usual suspects and minimize the potential for repeated codes down the road, which is why I am taking this approach. As far as the local dealer service dept, they want to charge $149 for a diagnostic fee and wont speculate without it (approached them before Christmas). The inspection is coming up in March and won't pass without a remedy. Hoping somebody who went down this path can help shed some light. Thanks again

 

Ok but you realize that you route should also include "ALL" the emissions hoses as well?
The reason they want a 149 is my guess to do an hour proper diagnostic which a good Mazda trained Technician will find you source of the DTCs.
We charge 135 one-hour diagnostic fee so your dealership is not out of line.

You also have not mentioned your monitor status? Which ones are not in state of emission readiness (which is in most states the testing looks at in the ECU on OBDII and CANbus systems) which can give you more clues to what emission part has failed?


When you replaced the parts did you clear the current DTC's? And also reset the monitors? IF not that would have been something you should have done.
Also as soon as the check engine light re appeared to retrieve the current DTC(s) before anomalies would likely happen that could cause other none part failed but a DTC to also be shown.

When you do a reset of the ECU monitors to get the correct information you need to do at least 1-3 cold start cycles.

As for the evaporation system Iam guessing from your comment of it being in "great Condition" you have the diagnostic tool (kit) check it ?

 

I hooked up smoke at the purge valve, waited until smoke poured out from vent valve, sealed off purge to vent and charged at 2 psi. inspected with mirrors front to back along all hoses, top of tank and canister with mirrors and bright lights. No love. Evap monitor not ready after P0442 or P0445 triggers. Erase codes, monitors all reset to READY after 1st drive, and the codes triigger anywhere from 5 to 25 or so starts later (1-3 weeks). Full diagnostic scan shows no pending or active codes after monitors reset. I feel I can rule out hoses since the trigger time varies. Leaning towards vent solenoid not fully seating every time or pressure sensor not performing consistently. Verified purge valve functions. Want to replace sensor and vent valve regardless of cause, so that is why I am posting for info specifically on them.

 

Wow! I am truly impressed.
May start shopping for a rebuild ECU? You can transfer all your Versa Tune to it>

This is mind you only a GUESS but you did all the leg work and a great job so that would be next item to look at. If you were in the shop I would do a pass-through and verify it on the ECU health but for you to get that done is almost as much as just getting a rebuilt ECU?
There are not to many places that can test or want to test a ECU but plenty of rebuild ones with reasonable warranties?

Remember this is a total guess I my part!

 

Thanks. Before I consider ECU, I would like to replace the vent solenoid first which is original and looking pretty rough considering its exposed location. I can hear it click during the start up evap pressure test but have no idea how well it is performing. It will likely disintegrate if I mess with it so I would like a replacement on hand. Hoping someone can verify KLG4-18-741 is correct for 2002 626 LX 2.0 . Also, no luck finding the location and part number for the fuel tank vapor pressure sensor. Any help with those these two items is much appreciated.

 

You will need the production date and the VIN. If you don't want to post it on open forum PM me

 

I would rather throw a few bucks (appx $200) to replace all of the usual suspects and minimize the potential for repeated codes down the road, which is why I am taking this approach.