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Mazda Millenia EGR problem



  • My 02 Millenia S (Miller cycle engine) CEL mystery was eventually fixed by replacing the gas cap. At my dealer it was $125 (don't try using a cheap one from your local auto store; pry open your wallet and use the Mazda one -- apparently there's a sensor that relies upon NOT having a dried out gas cap seal). Go figure. :shades:
  • t2tt2t Posts: 7
    I have a 2002 Millenia, which we purchased brand new. It's not the "S", so I have the 2.5L engine. I currently have 162,000 miles on the car. The last 3 years has been a real pain at getting my arms around the EGR / Check Engine light issue. I'm not sure why this car is so problematic in regards to the CEL being on nearly constantly. People shouldn't have had to suffer so much with whatever defect is presently causing the EGR issues. If I were going to buy a used one today, I'd get a written agreement from the seller that if the CEL comes on within 90 days of purchase, then it's their dime to fix it for you. I suspect many of the used Millenias out there have had some recent maintenance to clear the light and the owner got ill from the bill, so they put the car up for sale.

    Don't get me wrong, I'm pleased that I've gotten this many miles out of the car. However, one should also expect to be somewhat free of a car from getting a CEL so frequently. I've done everything possible to cure my P0400 (Generic EGR Malfunction) code to completely go away and it did for about 30 days over a 3-year period, which was long enough for me to get my emissions inspection passed for the next 2 years (I have about 10 months left to go) and then I'll need another emissions inspection, but I doubt if I'll be dropping big bucks into the car so it will pass. I'm very fortunate that I can do 90% of the work on the vehicle myself. To date, here's all that's been done to try to resolve the EGR (P0400) issue:

    1) Cleaned the EGR valve of carbon.

    2) Cleaned out the EGR chambers in the intake manifold.

    3) Cleaned out the two "snake eyes" that hide behind the intake butterfly valve.

    4) Replaced all of my vacuum lines (about 25 feet, total)

    5) Replaced the 2 solenoids for the EGR system (Vent and Vacuum solenoids).

    6) Had the BG EGR process performed ($250.00 at a shop).

    7) I removed the intake manifold and took it to a machine shop to have it dipped int their
    parts cleaner tank and then pressure sprayed to clean out any carbon.

    8) I replaced the EGR valve with a know used working one.

    9) Re-installed the intake manifold, but the EGR issues didn't disappear.

    10) I took it to a shop to have them look into the issue further. They claimed I needed to have my EGR valve replaced. ($750.00 in parts and labor).

    11) I was happy that the issue seemed to be finally resolved, right? Wrong! I had my car inspected for emissions and it passed. Then, a week later, the CEL light was back on. It's been that way for the past 14 months as I really don't want to work anymore on the P0400 code. It's impossible to cure on my car. I don't think throwing more cash into it is the answer ... only to get frustrated.

    I don't see myself buying another Mazda product in the future. A bit too expensive to get parts for - if you can find them. Currently, it appears the front pre-cat is no longer on the market unless you go to the dealership and buy it. The rear pre-cat is available from about 2 or 3 other 3rd party manufacturers.

    The EGR valve costs $400 at the dealership and is about $300 from Mazda discount parts places on the Internet. When I had my Ford Taurus, the most I ever paid for an EGR valve was about $65.00.
  • It could be one code triggering another code
  • Ddi you replace your EGR Sensor?
  • t2tt2t Posts: 7
    "Ddi you replace your EGR Sensor?"

    Greetings. If I could ask more specifically - which component is the EGR sensor on the Millenia? I've checked my replaced solenoids for the EGR (Vent and Vacuum) and they are within spec in regards to Ohms.
  • t2tt2t Posts: 7
    Hi, Sorry about the delay in getting back to this topic. I didn't replace the EGR Sensor, as I don't believe the Millenia has one - even though they have at least 1/2 dozen solenoids.

    I suspect, though, what you're referring to on the Millenia might be what they call the MAP sensor. That is a device, mounted to the back of the engine on the firewall and has one vacuum tube running to it. I believe most of the MAP sensors that I've seen on Millenias were made by Mitsubishi.

    I should probably spend a Saturday morning going to a "Pick and Pay" junk yard to collect some items for potential replacement. Though, there is always the risk of getting a part that's no better than the one you're trying to replace.

    This past weekend, I did buy an universal DC power adapter, though. Using that with my Millenia service guide, some aligator clips and spare vaccum hose, I'm going to follow through with the proper test procedures to determine if the sensors and solenoids are all operating properly when a load is applied to them. This will keep my from buying an endless supply of parts that might not need replacing.
  • Hey Buddy, i had the same problem.... I was about to get crazy, I've spent 700.00 in the last 3 days. I took my milly it to the shop and they did a full tune up, cleaned whole EGR SYSTEM, changed some bad hooses. I changed my Break rotors and pads, and reset CEL, The mechanic told me that my EGR System was ok and wasn't any reason to replace it, That the CEL shouldn't light up again, I was happy for a couple of days, right after I went to the gas station and filled up the tank.. boom!!! the light came again.

    I was continuing doing some research and it looks like the GAS CAP...yeah... The Old Gas Cap is not hold the correct vapor pressure and its making the EGR Sensor to activate the signal...

    So I want to a Auto ZONE and bought a new $10.00 GAS CAP, after few hours, the CEL went off.. Im loving my car again.

    I've also been reading that this did't work with some cheap gas caps and some of the guys with the same problem were forced to buy the original gas cap from mazda $125.00 but it did fixed the problem just by replacing it.

    I wish I knew this very long time ago, because I've been paying under the table to get my Emission Inspection Passed.

    I hope this works for you. ;)
  • t2tt2t Posts: 7
    Your post does seem encouraging. I've gone through the whole EGR cleaning process to the minute detail and still had many issues. I also purchased a new gas cap from AutoZone that apparently worked for about 2 days - then, bam, the light was back on again. I confirmed I didn't have any bad hoses, too.

    With that being said, I hit 165,000 miles on my Millenia about a month ago. I was kind of getting to the point of feeling a bit frustrated with many weekends of having the hood up on my car to get things situated - oil leaks, valve cover gaskets, etc. So, I was able to buy myself a newer Buick LaCrosse. I posted my Milly on Craigslist for $1,200 and it sold within 10 minutes of being posted.

    I liked our Millenia a lot, but locating parts was becoming harder as time passed. Also, the dealership doesn't charge $125+ for a gas cap. I believe that it's somewhere in the range of only $25.00. However, if you buy from - the Millenia parts are discounted and I think their price for the replacement cap was only about $18.00. I'm not affiliated with them in any way, but have been very happy with their prices and service when I needed them for my true / authentic Mazda parts.

  • Update to my previous post about changing out my gas cap to solve the CEL problem: After I questioned being billed $124 for a new gas cap at a Dallas metro area Mazda dealership, the service manager refunded me the $99 "diagnostic" fee. So yes, the OEM gas cap that says "Mazda" on it is actually only 25 bucks. And 3 months later still no CEL, so I'm happy.
  • t2tt2t Posts: 7
    Diagnostic fees ... Grrr. I can see where they're worthy at times if it will truly diagnose an issue - a small one, instead of replacing your motor. However, I feel that they're just another way for mechanics to generate revenue. Connecting a diagnostics tool and reading a few codes will take 5 minutes. Yet, you pay a minimum of 1 hour's worth of labor for it. Also, those "supply" fees and "disposal" fees can take a $25.00 oil change and make it go up to $40.00.

    However, the benefit in using the "true" Mazda cap is that you can continue to use the tether, if you like that feature. Some people who don't have a good memory will leave the gas station with their gas cap still sitting on top of the pumps.
  • jpland82jpland82 Lafayette,Louisiana Posts: 0
    Well I just got my Millenia S 2002 in January of 2015 found it with 45000 miles thought I got a good deal at 6500 basically in showroom condition then the 60000 mile service pack game come to find out it has two timing belts 2 water pumps and to serpentine belts brought it to the Mazda dealership here including a new alternator $2,900 now they did throw in showroom detailing to the car which was like oh what a hundred twenty bucks 2 brand new Yokohama tires 387 to new keys totally outrageous I think at a hundred twenty thousand miles she's going to get parked and wait for classic status but otherwise I absolutely love the vehicle and also my engine light is just coming on and
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