Okay, so let me start by saying this: I'm a girl and I know absolutely NOTHING about cars.

So my question is: assuming I can verify that it's the same stinkin' EGR code will it kill my car to just ignore it til it goes away again?

Here's my story:
Last November, I bought a used 2000 Protege from the Mazda dealership here in Minnesota. I was pretty happy with my purchase as it only had 63k miles on it at the time and seemed to be in pretty good shape. I even took it over to a 2nd mechanic during my test drive and he thought it was all good. Plus, the dealer was warrantying the car for 3000 miles so I figured I had nothing to lose. Well as my luck would have it, the check engine came on after about a week.

So I took it back to the dealer, they said it was an EGR code ("improper flow") and replaced the valve and cleaned it out for free (yay!). Drive it for another week, then it happens again. The dealer guys say "well maybe they didn't clean it out that well last time" and so they clean it out for me. Another week or two- ditto. they decide maybe the sensor's bad and replace it for me. Another few weeks- yep there we go again! This whole saga went on for several months. They replaced all sorts of parts in there, cleaned out the passages and even at one point they decided it was the car's computer and they replaced that for me too. After the 4th or 5th visit, they gave me a free loaner so that they could try their fix, and then drive the car a few hundred miles to make sure the light stayed off. At certain points, they kept the car for weeks at a time to work on it and drive it but they could never seem to get the light to come on for them. (I just drive special apparently) I didn't pay for any of this and spent a lot of time driving and racking up the mileage on a new Mazda3 they gave me as a loaner so it's not like they were at all profiting. There's all sorts of new parts down there now and I don't think they would have done that for ***** and giggles. I feel like after all that time/money/effort they were actually trying their best.

Finally, after 12 visits and 9k miles, they had replaced practically every component (it seems), had conferences with the Mazda "experts" in some corporate mechanic land and finally cleaned all the gunk out of the line. They told me they had put some special heavy duty carbon cleaner in there that would keep on working while I was driving it so that it would stay clean and keep cleaning out any additional carbon deposits they might have missed. They were absolutely positive that the freakin' light would stay off now. Well actually he said that at some point it might kick out the last of the gunk from the line and that might cause it to come back on but that it would only stay on for less than 100 then go off permanently. That was mostly true. I drove the car 4k miles the light came on for 15 miles, then shut off again and was off for several thousand more miles.

Well about 1000 miles ago, it started doing it again. First it was on for less then a hundred and then shut off. *rolls eyes* 2nd time it was longer. Third time about 300 miles before it shut off again. My car is at 80k miles now. The light is on again. I'm not sure the dealership will be nice enough to go through this dance with me for free now since according to them the problem was resolved 8k miles ago and they'll probably say its something I've done. Now, this problem was never really a big deal in my book. It didn't ever seem to affect performance and it isn't now. So now I'm wondering- before I invest my own money into this, is this something I can just ignore? Like what's the worst that could happen if I did?

I read somewhere that bad EGR flow can negatively affect your gas mileage. I monitor my MPGs religiously. When I first got the car I got 28.7MPGs. During the worst round of EGR problems I was down to ~26. With my last few fill-ups, with and without the light being on, I've been get 29-31MPGs. It does not seem to be a problem right now and the car is driving just fine.

Also can the type of gas I put in affect this? I did spend some time in Wisconsin and Iowa this summer and I know they put different stuff in their gas. I think it has more ethanol than Minnesota gas or something like that. I tried to stay on the Minnesota side but last two times I didn't quite make it back to the border so I did get gas once in Iowa and once in Wisconsin. (Just half tanks and then Minnesota gas in between the trips.) I noticed that if I use the BP by my house I tend to not have issues. (Coincidence?)

I don't have the time/energy to go through these shenanigans all over again with this wacked up car, especially if it doesn't seem to do anything either way. So assuming that I can go get a code scan to verify that it is the same code (P0440), and that it's still driving fine and no performance metrics(like MPG) are being affected- can I just keep driving it like this? It sounds terrible but I'm just about ready to accept that I have one of those hypochondriac phantom "check engine" cars.

 

P0440 is not egr, its evap, make sure your gas cap is sealing. google the exact code and it will tell you the possible problems. get the exact code then you can solve your problem. get the code and I can sell the parts you need to fix it.

 

Thanks at least for replying! Sorry I'm not sure I typed the code up exactly right. It might have been P0402? 0240? The receipts are somewhere in my trunk right now. Whichever number it actually is, the exact code description is "insufficient exhaust gas recirculation flow" when you google it. I've got the mechanic receipts to prove it too, it's always the EGR code.

Trust me, I've tried the gas cap thing, no go. The mechanics have replaced literally everything else so it's not simply a matter of "selling me parts". The only thing that seems to help is to just keep cleaning out the EGR passages when the light goes on which I don't know how to do so I have to pay the mechanics to do it. So my question really is: before I go through all that trouble, is it even gonna make a difference? My car is driving fine.

 

First off, the Protege is one of the cars I specialize in. I'm not trying to sell you something for the sake of selling something. You have a problem that wasn't correctly diagnosed or repaired properly.

When you stated, your mechanic replaced the EGR and cleaned it, this sounds contradictory. A new EGR valve doesn't need to be cleaned as it's brand new, which is a red flag to me. Also, they must check the EGR return pipe to make sure it is not clogged as well. The EGR system is important as it affects gas mileage and emissions.


In the long term you be better off fixing the problem now. You will never know if something else goes wrong with your car if you have a constantly on check engine light. Yes, it's worth the trouble to fix the problem. Your car is running in a limp mode where it will have reduced performance, uses more gas, and increased emissions.
Overtime, if unfixed it can lead to other engine reliability problems. So fix it cheaper now or fix something more expensive later. You can use any 87 octane E10 gas, but if you don't fix this you may have to run higher octane from the EGR not working and causing knock.

The correct code matters more than having the correct description to a technician as it affects the diagnostic process because many people write down an incorrect description as there can be other related code descriptions.

Which engine do you have in the car? a 1.6 or 1.8?
Was the dealer you were dealing with a Mazda dealer? If not take it to one to get it diagnosed.
Did they use a factory new EGR valve or just clean it? A factory Mazda new part should not have failed already. They carry a 12 month/ 12k mile warranty from Mazda.

 

Sorry don't mean to get snappy, just trying to get to the heart of the question and also explain that I wouldn't even know where to begin fixing it myself. While I'm fairly confident that the guys at the Mazda dealership did their repairs correctly, you're probably on track with the misdiagnosis. However, after 12 trips to the dealership, during which they called other Mazda dealers to ask other Mazda experts for opinions, I'm not all that confident that it ever will be diagnosed properly hence my current attitude towards just leaving it be.


Sorry to sound contradictory, I was simply trying to paraphrase the saga that was 12 trips to the Mazda dealership. The first time I went in they said it was the valve, so they replaced it. The second time they said that they had missed some of the carbon in EGR system the last time, so then they had to take everything apart again to clean it. (the return pipe was mentioned somewhere in there so yes that was cleaned out). 3rd time I went in they said maybe it's the sensor- replaced that. 4th time- not clean enough- scrape scrape scrape. 5th time- the pipe... you get the idea? After awhile I did sort of lose track of all that they did, I have all the receipts somewhere if you're interested I guess. They replaced valves, pipes, sensors, even the car's computer. It got to the point where I'd just show up, pick up my rental and come back later to pick up my car with a "see ya next week"attitude in mind. The only thing that did ever seem to keep that darned light off for extended periods of time was when they would take it apart, clean out the carbon and then coat the system with some carb cleaner to keep the build up from sticking again. (Thats what they did the last time and it lasted for quite awhile) Eventually though, the light comes back on again and it's always an EGR-related code.

As for affecting gas mileage and emissions: Can't say for sure about emissions since I don't regularly stand behind my car while driving it but there haven't been any unusual clouds behind me and my MPG seems fine. I monitor MPG religiously since I do a lot of driving (its a long commute) and I like to see how my driving is affecting my MPGS. The car is rated at 23/30 by the EPA- (26 combined) and after my last two fill ups I've been at 30-31 and I am living in the city. Either MPG is not effected or my car has greater potential than what the gov't says? I've been forewarned about the MPG-EGR relationship so I've been monitoring that pretty closely.


Thank you. This is really the answer I was looking for. Though in my defense MPG and emissions seem fine and I have been taking it to NAPA to get free code scans when the light is on because I am paranoid about other engine problems. (It turned off again two days ago!- crossing my fingers now!) I wouldn't mind taking it to get fixed, but since I've already gone to the so-called Mazda experts in the city, I'm not confident that the next thing they do will be worth the money. I guess I'm looking for ideas as to what to suggest to them, otherwise I'm just going in for an EGR cleaning since that seems to be the only thing that ever works. At this point the Mazda people have replaced a lot down there and I'm thinking that the EGR-carbon problem is really a symptom of something else. (Where is all that carbon coming from??) Suggestions please!

I don't know what knock is supposed to sound like but I haven't heard any weird noises yet (i think). Last time I filled up, I used 89 octane with some carbon cleaning additive in there- dunno if that helped but hey my light is off now! I only did the 89 because the gas station by my house sells it same price as the 87 (not sure why) and the guys at NAPA sold me the SeaFoam Cleaner. Not sure if this is something I should keep doing. But it's pretty much my reason for wondering about gas quality.


I'm bad with number but good with words. I'm 99.9% confident that that is the right description but if it really matters I'll go dig up one of the receipts again.

It's the 1.6. Automatic if that matters

It was a Mazda dealer, who, (during my 3 month, 12 trip saga) also called up other Mazda dealers in the city for advice and apparently some mechanics in Mazda corporate land. I'm actually considering taking it to a different mechanic next time since I've had such rotten luck with the folks at Mazda. But again, if I do this, then I'm going to need suggestions as to what there is left to fix.

Since it was a Mazda dealer, I'm assuming it was a Factory New EGR valve, especially since they paid for the eleven visits after that one. And uh, 12k miles is what I drive in 6months so I think I'm past that....

Sorry if I ever at all sounded snappy but after dealing with this for so long I'm just touchy about the subject in general. My car seems to have everyone stumped and I'm frustrated as f***! This has kind of been what's led to my "just leave it be attitude" I need more ideas!

Thanks!

 

Since you dealt with a Mazda dealer. Contact Mazda customer care. Tell them of the problem you are having with a recurring problem that the Mazda dealer has not solved.
1-800-222-5500. This route should get you somewhere.

As for the emissions. It's not going to puff out clouds of smoke. The NOX is not visible.
The MPG may not be affected much now, but it can decrease if this problem is not fixed soon.

There is a technical service bulletin for your 1.6 engine regarding the EGR.
http://www.protegefaq.net/tsb/01-007-02.html
This should arm you with some info Mazda techs have.

Good luck and come back with some good news.

 

Also, they should probably check the spark plugs, ignition leads, MAF sensor, air/fuel filter.

If the EGR operation is tested normal and power wires are good, but still has a sooty exhaust gas mixture, there maybe an underlying fuel/ spark problem.
Also, see if there is a PCM calibration update.

 

Thank You! The light is off right now so we're back to "wait and see mode" but I will try the other things if comes back on again. (been 300+ miles off so far!!)

As for the things you mentioned: the MAF sensor has been cleaned (and then replaced when that didn't work), and the PCM is also brand new. Air Filter was changed a month ago so I think we can rule that out. Just to be on the safe side, I will have them check the fuel filter during my next oil change. Spark plugs are one thing I do know how to do so maybe I'll pick up some new ones since that's also another cheap and easy thing. (I know a few basic car things: topping off fluids, wiper blades, battery/spark plugs, headlights and the air filter. I can also jump a car and change my own flat. Awesome Girl Power right? LOL)

That service bulletin actually sounds pretty familiar. It sounds exactly like what they were describing to me when they were telling me was wrong with the car and what they were doing when they were cleaning it. I just dont "speak car" so I cant be sure but it sounds like that's what they've been doing. The problem seems to be that it keeps getting sooty so I think you're right on target. From their accounts, the EGR seems to test normal but I still get carbon build up that needs to be cleaned out. I'll give my dealer another shot and if that doesn't work I'll call that number. (And maybe I'll suggest to them the ignition lead thing too.)

Thanks again for all your responses.

 

Tell them of the problem you are having with a recurring problem that the Mazda dealer has not solved.

 

Did you know that your Protege will throw a CEL (check engine light) if you don't screw the gas cap on until it clicks? This happened to my wife's '01 Miata.
We had to take it to the dealer to have the CEL cleared, but it's never come back since she started using that simple trick. Crank that sucker all the way down!

 

Yeah my old civic used to do that too. (I had to do three clicks with that one actually) So yeah, now that's the first thing I always try. I've cranked that sucker pretty hard!

The light came on again last night on my home from a friends house but when I went back to drive it to work this morning it was off again (and I have a 30 miles commute so it had plenty of chances). Honestly, I think this car just wants to drive me insane!

Also, to go back to the original comments, the codes that keep showing up on my receipts from the dealer is P0420 and P0402. Considering that tech services bulletin that Crossover linked me to, I'm betting on a dyslexic receptionist and that it's really P0402 all the time.

 

I would go to a local autozone or any other major chain parts retailer. Get the code scanned for yourself and the exact code. Sounds like the technician is entering the wrong code on the work order.

The P0420 says you have a bad catalytic converter.
The P0402 is the EGR.

 

Its looks like a great one. I feel it will be a good option only.