EGR Problems! 91 Accord EX... Code 12
 

Hello... Just had a question about my 1991 Honda Accord EX 2 DR (220,017 miles). The engine in it is the f22a4. Just wondering about my check engine light. I checked the check engine light and I'm getting 1 long flash and 2 short blinks meaning 12 which is EGR system. I took the egr valve off and cleaned all carbon out, there was just a little inside the intake manifold and the valve. I replaced the gasket. I cleared the check engine light and drove it again, light came back on still egr system. The egr valve does hold vacuum, something I checked when I had it off of the car. What other things do I need to do to get the light to stay off. Map sensor? Also, is there any easy way of checking to make sure my intake manifold is not blocked with carbon besides drilling out the plugs? Any help would be greatly appreciated!! Have a good day.

1991 Honda Accord EX 2 DR
1991 Honda Civic Hatchback Si 3 DR

RE: EGR Problems! 91 Accord EX... Code 12
 

I have the same problem and i am yet to figure out the problem, check you control box, also check for low voltage. I had the problem right after i cleaned the system of carbon, make sure the metal plate over the egr holes are bolted tight. mine came loose, and make sure its not ur EGR itself that is not bad, check this by adding the 15' hose to the valve while engine is running if that make the engine stall then ur valve is good, if not then replace.

RE: EGR Problems! 91 Accord EX... Code 12
 

Code 12 means the ECU did not detect EGR valve movement consistent w/ command to open EGR valve by ECU. This usually means that vacuum is somehow not getting to the EGR valve or EGR valve is damaged. This may be a broken vacuum line, non-functioning EGR vacuum switching solenoid valve, or broken EGR valve diaphragm. To determine which, first check for vacuum to the vacuum switching solenoid valve. If Ok, next connect vacuum directly to EGR valve (bypassing the vacuum switching solenoid valve) and see if EGR valve moves (opens). If yes, the vacuum switch solenoid valve is not passing vacuum. This probably means teh vacuum switching solenoid valve is defective and must be replaced.

The Online Manuals has links to a 91 Accord manual from hondahookup.com.

good luck

RE: EGR Problems! 91 Accord EX... Code 12
 

So I did some research in my Haynes manual. I jumped the connector for the EGR control solenoid valve. It says to jump the connector and then have a vacuum tester on the #16 hose that leads to the EGR valve. After I jumped it the vacuum increased instantly. So this rules the EGR control solenoid valve out right??? Does vacuum open the valve or does the sensor on top if the EGR valve??? Any help would be greatly appreciated! Thanks for your time!

RE: EGR Problems! 91 Accord EX... Code 12
 

I have seen many lift sensors bad on those EGR valves, I think the manual shows a resistance test to do while manually lifting the valve.