Yet another code #12 problem

[allhailmj23]

I am at ends with my car. I've always had a problem with this CEL. 2 years ago, I replaced the whole vacuum box and put in clean little filters, and the CEL still came on. 2 months ago I had a brand new EGR valve installed, even though the old one was holding vacuum perfectly. Still no fix and I was $300 poorer. Then I brought my car into a Honda specialist shop to get it diagnosed and they said that a couple of the solenoids in the vacuum box were the culprits. Just put in another junkyard vacuum box and CEL still persists. Yes I've used the search, for the past 2 years in fact, and still no dice. The link to the troubleshooting pdf is dead. So I hate to be a noob, but please help!

[2geeSEi]

Are you sure that the solenoid is getting power?

[Gt-r]

Buy new solenoids. You run a 50/50 change of a junkyard item being worth anything and not a peice of shit.

[2geeSEi]

You can also use a 9v battery or car battery to check whether the solenoid is working. Also, check for battery voltage between the black/yellow wire and body ground on both the solenoid connector and the lift sensor connector.

[Dr_Snooz]

I am at ends with my car. I've always had a problem with this CEL. 2 years ago, I replaced the whole vacuum box and put in clean little filters, and the CEL still came on. 2 months ago I had a brand new EGR valve installed, even though the old one was holding vacuum perfectly. Still no fix and I was $300 poorer. Then I brought my car into a Honda specialist shop to get it diagnosed and they said that a couple of the solenoids in the vacuum box were the culprits. Just put in another junkyard vacuum box and CEL still persists. Yes I've used the search, for the past 2 years in fact, and still no dice. The link to the troubleshooting pdf is dead. So I hate to be a noob, but please help!

No mention here of going through the troubleshooting flowcharts for a code 12 in the manual. Those are always my first stop when dealing with any CEL codes. They will guide you right to the specific faulty part and include all tests for verifying that it is indeed bad. About the only EGR issue not covered in the manual is carbon buildup in the intake channels, but that shouldn't give you a CEL. Spend some time with the manual and see if you can't figure it out. We have one for the '89 model year available on the wiki, but the EGR system is somewhat different. I would recommend that you buy the right one for your car (then scan it so we can post it on the wiki for others).

If I may, avoid shotgun fixes where you simply replace a bunch of stuff that might be bad. Learn to test and verify specific parts and replace only those parts. It will keep costs down and won't introduce new, potentially bad parts to the equation. If you don't have the tools to test and verify, buy them. It will be far cheaper in the long run. For this problem, you shouldn't need much more than a vacuum pump with gauge and a multimeter.

Let us know what you learn.

[2geeSEi]

Yeah, Dr. Snooze, I suggested that to him a couple of months ago. He has eliminated a couple of the steps by putting the new EGR on, so the suggestions that I made were the next steps in the troubleshooting. The part where it becomes a little more difficult is when they tell you to connect the test harness at the ECU. If he has voltage to the solenoid and lift sensor, the next step is to test for continuity in the wires back to the ECU, so without the test harness, he will have to find the correct pins to probe for the continuity test. I agree though, one shouldn't just throw parts at it hoping that it eliminates the problem. Especially expensive parts.

[Dr_Snooz]

Ah, yes, the mythic test harness. That's always a fun step.

Didn't realize you were working on this issue previously. OP is in good hands.

[Jafir]

9 times out of 10 on a 1986 or 1987 accord lxi the egr code is set by a little white plastic "chamber" a round can with I think 3 vacuum lines hooked up to it. Take this chamber out and clean it. One of the ports will be completely or almost completely clogged. I used to use brake cleaner, but some just used compressed air.

[kentwat]

9 times out of 10 on a 1986 or 1987 accord lxi the egr code is set by a little white plastic "chamber" a round can with I think 3 vacuum lines hooked up to it. Take this chamber out and clean it. One of the ports will be completely or almost completely clogged. I used to use brake cleaner, but some just used compressed air.

That was the problem with my 86. I changed everything. Then broke down and went through the testing above and the little green (cvc)? vacuum pod was bad. I had another one and code went away.

[carotman]

I have this same trouble code on my car. Never bothered to fix it but all sings points to this little chamber. I'll try it and keep you guys updated.

[gp02a0083]

had a similar problem with my 87 FI hatch after a really dusty summer. turned out that the solenoid just needed cleaning of the little tiny filter and it was fine years later when i sold it

[allhailmj23]

Yeah I've been through 3 of those white and green disk things with no success. Anyhow, I was able to pass my smog test on my second try. The smog tech was kind enough to disregard the CEL since our cars are obd0 (at his own risk), but the NOx at 15mph was too high by about 150 points (out of 825 max). Came back again a week later with tank full of 91 octane and a bottle of isoheet, and the number dropped to 812 points in NOx, so I barely passed. Anyway thanks for the help guys! I'll need to refer back to this thread 2 years from now with my next smog test...

[Jafir]

Yeah I've been through 3 of those white and green disk things with no success. Anyhow, I was able to pass my smog test on my second try. The smog tech was kind enough to disregard the CEL since our cars are obd0 (at his own risk), but the NOx at 15mph was too high by about 150 points (out of 825 max). Came back again a week later with tank full of 91 octane and a bottle of isoheet, and the number dropped to 812 points in NOx, so I barely passed. Anyway thanks for the help guys! I'll need to refer back to this thread 2 years from now with my next smog test...

In my experience, not the green disk, it's a white or clear chamber. See this photo: Honda online store : 1987 accord air cleaner vacuum tubing (pgm-fi) ('86-'87) parts

The green disk is number 1, I'm talking about number 9. Take it out and inspect it. I usually cleaned the ports with carb cleaner, but someone once told me that might be bad for the plastic, and that they just used compressed air.

[rodan32]

Thanks, Jafir - I was just about to ask for a picture. Does the '88 LXi have the same issue? I'm having a similar problem, and it looks like it might be #11 in this diagram that would get fouled up: http://estore.honda.com/honda//image...SE03B0110A.png

[VIPER1988]

Just fixed mine. Ended up being a clogged vacuum chamber.


used phone light so u can see the tiny hole inside.

Mine was clogged with a greasy substance and wouldn't blow out with compressed air. I used a very fine needle to push it through then put some rubbing alcohol in it to clean up the rest.

[Jafir]

Thanks, Jafir - I was just about to ask for a picture. Does the '88 LXi have the same issue?

My experience it was just the 86 and 87, but anything is possible I assume. I'd run through the egr tests in the FSM to be sure.

[Jafir]

Just fixed mine. Ended up being a clogged vacuum chamber.

That is a great write up.