Code 12 , Egr Valve Trouble

[rosenfield.9]

Hey guys. I'm having a problem with my '87 Accord LX-i. Here's the story....

The PGM-FI light started comming on back in February with a code 12, EGR Valve. I brought the car to Honda who troubleshot the EGR system and they told me that the CVC Valve was not holding pressure and it needed to be replaced. I had them replace it and the light went out for the rest of that day. The next day the light came back on with the same code, so I took it back to the dealer. They troubleshot again and determined that the EGR Valve itself was not holding a vaccum and needed to replaced. I had the dealer replace the EGR valve.

The PGM-FI light stayed off for about three weeks until I needed to replace the main wiring harness in the engine to correct another problem I was having. This harness goes to everything in the engine (headlights, turn signals, distributor, fuel injectors, egr vavle, everything). Three days after this was replaced, the light came on again with the code 12. I don't know if the new Honda wire harness was the cause of the problem. Since then, I have checked all of the connections, brought the car back to the mechanic who put in the wiring harness to check all the connections, and checked all of the vaccum hoses going to and from the intake and to the EGR valve. I can't figure out what's wrong.

I am going to call the Honda dealer who did the original EGR work and see how they want me to proceed since I am in Ohio now and the dealer is in Atlanata. I am wondering I can go to any Honda dealer to have warranty work done since I believe Honda's work comes with a 12 month, 12,000 mile warranty. Remember, there is a new Honda EGR valve, a new Honda CVC valve and a new Honda wiring harness. I was thinking about getting a EGR control Solenoid and replacing that since it is the only other part in the EGR system that can be replaced. Feel free to post any suggestions about what else you think may be wrong. Thanks for your help.

[Autowiz]

egr is an acronymn for Exhaust Gas Recirculation. as the exhaust gasses pass from the exhaust over to the intake, aside from the drastick temperature change, wich eats up rubber diaphrams in egr valves, there is also the carbon deposits left in the egr passages in the intake manifold. if you remove the two bolts and take off the egr valve, you'll be able to see inside the intake manifold, if the passages are clogged, then the egr system will experience insufficient flow, and that could make your code 12 pop up. the problem with egr diagnostics are the valve only opens under very specific conditions, for example, if you only drive in town, and never go long distances, it's possible a egr valve could be bad for days, weeks, or more, without the mil light comming on. the valve only opens at highway speeds, on decelleration, with the car fully warmed up. but for diagnostic purposes, if the vacuum lines are all connected, the control solenoid is good, the valve is good, and the wiring is all on point, the only other possible cause, aside from a crudded up intake, would be an internal pcm failure, and while as a four time a.s.e. certified tech, i want to tell you it's probably unlikely for a honda pcm to fail, if you had issues with the main wiring harness, it is more than possible to have shorted the wrong circut to power or ground, and to have burned a portion of your pcm, but if that were the case, i'm sure there'd be other drivability issues.

[rosenfield.9]

I know this is a dead thread but just an update for those of you who are having this problem and looking for help.

I took the car back to a Honda dealer in Columbus, OH. They said the parts that have been replaced (EGR Valve, CVC Valve) were working properly. They suggested that they clean out all the lines, valves, and filters since sometimes they get clogged. Well an hour and $190.00 later they fixed it. The filter that is in between the EGR valve and EGR solenoid was clogged and this prevented the vaccum from working properly. A week an a half later, no problems. I believe that the clogged filter may have been the problem all along but even the best mechanics need to troubleshoot. Anyways, good luck with your EGR problem. Hope this thread helped.

[Autowiz]

if you have a digital volt/ohm meter, and access to a wiring diagram for your car, you can measure resistance from the pins in the pcm harness to the plug on the vacuum control valve. a break, or resistance greater than 1 ohm could cause problems with your egr system.

[DBMaster]

Got a check engine light last night. It is intermittent right now. 12 blinks on the ECU which the shop manual says is "EGR System." I have not yet gone through the diagnostic procedure, but it looks like it can be a number of things including one of the control pieces in the "mystery box."

I thought I would ask first if anyone else here ever got that code and what they had to do to fix it. There do not seem to be any driveability problems or idle issues related to this.

Thanks!

[DBMaster]

Thanks for the response! Will the car pass emissions without an EGR valve?

[86-accord-lxi]

I have an intermittent "pgm-fi" light.
The ecu flashes "12" too. no "check-engine" ligh though.
I recently replaced the fuel filter. I had half a tank of gas that was in the car
when it sat for a year or 2 . I topped it off with fresh gas and lucas fuel system treatment. The pgm-fi light stayed off after that, and the ecu code
"12" stopped flashing. How long since you changed the fuel filter?

[DBMaster]

Actually, I just changed the fuel filter Saturday. The light came on driving home from work last night. When I restarted the car later it stayed off. It came on again this morning, but went off when I restarted the car. The idle does not change at all so at least I have time to mess with it.

[shepherd79]

the idle won't change on 88-89 efi motors. i have notticed over the period of time that people with 88-89 EFI engines don't have problem with idle as myself. I have 86 EFI engine and when EGR tripped, i had big idle issues.
1. remove the valve and clean it with carb cleaner. make sure it moves up and down without any problems.
2. make sure you reset your ECU after you install the EGR valve back in the engine.
3. use vacuum pump to see if the valve itself is holding the vacuum. if valve doesn't hold the vacuum, replace it with the one that does.
4. if you still have code after you checked out the valve, it is time to open the mistery box. follow the vacuum line and you will find the controller. replace the controller.

i hope that helps

[DBMaster]

The shop where I sometimes take the car says that it is far more often the controller solenoid in the mystery box (I love that term!). I can actually check the EGR pretty easily. This may be of value to others. I found this in the shop manual several years ago. If you have a hand vacuum pump you can connect it directly to the EGR valve. With the engine running pull a vacuum. If the engine doesn't die immediately you have a bad EGR valve.

I will be testing my stuff in the next day or two once I have time.

BTW, they told me that even though you may not have any driveability issues with a malfunctioning EGR system you would fail the NOx emissions test big time.

Thank you guys!

[DBMaster]

Well, the EGR valve held vacuum and killed the engine when I tested it. I went through the rest of the diagnostic and near as I can tell it's the EGR control solenoid. I ordered one from Majestic ($108!). I sure hope it does not turn out to be the CVC valve after I go through the expense of replacing the EGR control. Pretty sure that's what it is, though. I suppose I could have gone on a junkyard excursion for it, but I hate installing used electronic parts.

[DBMaster]

I reran the diagnostic process and decided to go ahead and get a new CVC valve, too. Since it was not very much money compared to the EGR solenoid, why not? Something that I noticed recently might be related. For most of the car's life (I have been driving it for 16 years) when you turn off the engine you would hear a noticeable "whoosh" sound coming from the area of the mystery box. A couple of years ago I noticed that I could not hear the sound all the time. Maybe that is some kind of vacuum bleeding going on after the power is cut to the control valves. So, maybe I will get lucky after all and find that one of the valves is indeed faulty. When the engine is hot and you coast it sometimes has an up and down idle speed fluctuation that even the Honda dealer could not diagnose. Could be that this is related. Wouldn't that be nice?

[rosenfield.9]

I had this problem on my car. I went to Honda twice, once they replaced the EGR valve and once the CVC valve. I still had the same problem with the light comming on (Code 12). I copied the next part from the post I made a while back

I took the car back to a Honda dealer in Columbus, OH. They said the parts that have been replaced (EGR Valve, CVC Valve) were working properly. They suggested that they clean out all the lines, valves, and filters since sometimes they get clogged. Well an hour and $190.00 later they fixed it. The filter that is in between the EGR valve and EGR solenoid was clogged and this prevented the vaccum from working properly. A week an a half later, no problems. I believe that the clogged filter may have been the problem all along but even the best mechanics need to troubleshoot.

Anyways, good luck with your EGR problem. Hope this helps.

[rosenfield.9]

Here's the link to my original thread.

http://www.3geez.com/showthread.php?t=43583

[DBMaster]

Odd. I see no filter in line between the EGR solenoid and the EGR. There are three filters in the mystery box that filter air coming in when the vacuum is release, but, as expected, they are pretty clean because they are in a nearly hermetically sealed plastic enclosure. In my diagnosis process I learned that it is possible for the vacuum chamber to get a clogged port, or for one of the valves (CVC or EGR control) to get a bit "sticky." Of course, now that I have messed with it, disconnected hoses, jumpered wires, etc. the Engine light is off and staying off. Just my luck that I might have cleared a blockage and have spent money on the parts anyway.

The PGMFI system on this car is a beautifully reliable thing. It's just too bad that when there is a problem it's such a pain in the ass to figure out. None of the fixes are ever difficult, only figuring out what to fix!

[DBMaster]

Damn! I replaced the EGR solenoid and CVC valve. The hoses are all in good shape, I have proper vaccum pressure, and there is no junk in the little plastic air chamber. Got the light again, five minutes into my morning drive. I can say that the little roughness in the idle is gone, but the ECU still "thinks" there is something wrong.

EGR lift sensor? Wiring to the EGR or mystery box? It sucks that this is happening when the car runs so well. I guess a trip to Danny's Import Service is in my near future after tossing $180 at this.