For the past 2 weeks or so, my "Check Engine" light comes on after a couple minutes when I crank my car cold. If I park if and let it sit for a few minutes then turn it back on, the CE light doesn't return until I let it sit again over night.

I checked the error code and got

Error Code 12 = Exhaust recirculation system.

After searching the internet, I found that I needed to clean out "Exhaust Gas Recirculation" valve and manifold.

When I took the assembly apart, the manifold was completely clogged up with carbon. It was as if someone had poured concrete in the holes.





After I cleaned the openings in the manifold.


After cleaning out the manifold and the valve, I reset the computer. I was then able to drive the car around for 2 days. But then the check engine light came back on.

I did some research and found that another common problem with error code 12 is the Vacuum hoses. So I replaced all of the vacuum hoses. Reset the computer again. Once again, I got 2 days out of it, then the check engine light came back on.

What else can I do to make this check engine light go off and stay off?

 

The problem could be faulty parts or perhaps a blockage that you missed.

Suggest downloading the 94-97 Accord manual from Online Manuals post in DIY forum. Pages 114-119 present diagnostic tree to resolve where the problem lies.

For a "short version" check whether vacuum applied (orally or w/ vacuum pump) to EGR vacuum port opens EGR and causes running engine to stumble. This would indicate the EGR valve is working and EGR passages are open. A blocked passage or stuck EGR valve is a possibility.

If system is open, fault may lie w/ EGR vacuum switching valve (not actuating on command), or vacuum source (blocked or leaking).

It's also possible the valve lift sensor is faulty. If other parts check out, this would be next.

good luck

 

The actual EGR valve is good. I've had it tested. Is the vacuum switching valve the same thing? Or is that a completely different device. If so where is that hidden.

 

That's why you need a manual. Much easier to see a pic and find the device than for me to describe a location.

Yes, EGR vacuum switching valve is different. It enables vacuum supply to EGR when ECU commands EGR flow. Vacuum opens EGR valve allowing flow.

EGR vacuum switching valve is located on driver's side top of fender well. You should be able to trace vacuum line from EGR to vacuum switching valve.

good luck

 

Oh. Yes. I remember replacing the hoses on that device.

How much would a replacement cost?

 

You don't know vaccum switching valve is faulty. It may be faulty vacuum line or vaccum control valve.

Check first that vacuum is available from Vacuum Control Valve (upstream of Vacuum Switching or Solenoid Valve) to the Vacuum Switching Valve w/ engine idling. You need the manual schematic to understand the terminology and locations.

good luck