2012 Honda Civic Sport 1.8L (R18Z4) euro-spec. 6-speed manual. Hatchback. Fairly low mileage at 58k miles (93k kilometers). I've had this EGR issue for a while where it is often stuck open 99%, while commanded EGR value reads 0%. This is usually at idle. While driving it will close when I let off the gas. Cleaning the EGR valve does not help. So I decided to buy a new one (aftermarket German brand Febi Bilstein). Original Honda is very expensive and hard to come by, so I decided to try this one.
After replacement, my diagnostic computer was showing that it was working properly at various driving speeds. It was working as the commanded value said it should be. However, I developed a very severe lean condition with ST fuel trim jumping to 48%. Eventually, LT fuel trim started creeping up as well to high levels the longer I drove, eventually throwing a code P0171.
I did the idle re-learn procedure several times but that did not help.
I went back to my old EGR valve and lean condition went away but now the EGR valve went back to its previous behavior of not closing when needed.
Why did I get such a high lean condition after putting in a new EGR valve? The EGR valve is not directly involved in the fuel mixture but if it was malfunctioning then it could allow too much air into the system and indirectly causing a lean fuel mixture but the diagnostic computer was showing it operating properly. So I don't know what's going on. Please help!
For a critical part like the EGR valve OEM is best.
@chucktobias Of course, but the OEM part is insanely expensive here in Poland. 3,087 zł (PLN) which is an equivalent of $764. I will recheck my installation, maybe there is a leak somewhere? But the installation itself is very simple. Unplug the connector, two bolts, a gasket at the bottom and that's it. 10 minute job. Not sure where it could have gone wrong 🤔
If there are no leaks the new part may be defective. Happens all the time in the U.S.
If the Honda-branded part is too expensive, a replacement from the actual part manufacturer is the next best thing. (For a Japanese car it's frequently Denso,but there are others.) Usually less expensive and the same exact part as Honda would sell.
@chucktobias Just a quick follow-up. Did a smoke test which showed a direct leak coming from the EGR valve itself. Strange thing is that it's in the exact same place in the old one and the new one (non-OEM). I wish I could add a photo but I don’t see an option to do so here but you probably will know what I'm taking about. The valve is made of two parts, a baseplate on which sits the main EGR body that are connected by several screws from the bottom. In between there appears to ba a gasket. It's from that gasket where smoke was pouring out in both instances. I'm assuming this is not correct and these two parts should be sealed air tight?
It's very curious that the leak is in the exact same place on both parts. I'm assuming the non-OEM I bought is remanufactured, rather than new and it was not done correctly.
I tried tightening the screws but they were already very tight, so it's probably the gasket in both cases and that gasket does not appear to be replaceable. Any advice? Am I just doomed to buying the super expensive original from the dealer?
Modern EGR valves work based on computer-moderated engine vacuum, I'm pretty sure. I know that on old-fashioned carburetor cars, EGR valves will open and close based on manifold vacuum.
If your EGR valve has a vacuum leak, it will change the operating parameters in the engine and cause it to run lean -all vacuum leaks throw off the MAF sensor's readings and cause a lean condition. Additional, unmetered air is being sucked into the engine.
I would also check for vacuum leaks if the hoses are original to the car. They're 12 years old at this point.
@justin-shepherd I will check for leaks as you suggested. Just ordered a smoke machine which is relatively inexpensive. It will come in handy for other home uses as well. Maybe the new EGR valve was not seated properly during installation, causing this massive air leak? I installed back the old one and although the error code P0171 is not coming back, there is still a moderate lean condition of around 10% on LT fuel trim, where previously it was fluctuating between 3% to 6%. Maybe this is normal for Honda's? We'll see what the smoke machine shows. I hope the new EGR valve is working properly and it's just a simple air leak because an OEM EGR costs an equivalent of $764 (3,087 zł in Polish currency), which is totally insane.
I wish I could add a photo but I don’t see an option to do so here
Instructions for photos are hidden in a post near the top of the main page with the title "READ THIS FIRST - Forum Guide".
@chucktobias Thanks for this! I don't use these forums very often. Here's the image link: https://ibb.co/W2z07Mb
Also, I contacted a local Honda dealer who confirmed that the EGR vale should be completely sealed and airtight at the point indicated in my photo. Additionally, in his original email he gave me Honda's catalog number for this part: 18011-R1A-A00. I found it in multiple distributors of original Honda parts in the U.S. and it costs around $170 on average, which is four times less then here. This is insane!!! I think I'm just going to order this part from the U.S. and with shipping and duties it will still be 1/3 the cost here. I looked in other European countries and could find nothing other than substitute non-OEM parts.
Doing a bit more research, it appears that this is a fairly universal EGR valve, used in various models and engines from 2012 to 2022. I'm assuming that part number is the same globally, since it comes from Honda, so it should be same whether buying it in the U.S. or Europe. What do you think? Any advice would be much appreciated.
@piterek1973 If you can import the factory part for not too much money that sounds like a good approach. The only downside is that if you get a bad one now it has to be shipped back overseas. (Even factory parts these days are defective all too often.)
@chucktobias I'm concerned about the same thing. However, it may have to be a risk I need to take. On the other hand, there may be a cheaper solution. I know that my old EGR valve as well as the non-OEM one that I still have, appear to be mechanically sound, so what if I take a high temperature sealer, something like and exhaust system cement that can withstand temperatures of 1200 Cº (2200 F) and seal up that place where it's leaking? Could be a cheap and easy solution. Have you ever heared of something like that being done? Any recommendations on a product to use?
@piterek1973 I have my doubts as to whether that would work, maybe you could try furnace cement.