I have an 89 CRX HF and have been getting a 12 code on the ECU. I ran through the troubleshooting section from the Haynes manual I have. First problem is when I put a vacuum on the EGR valve the engine doesn't stall like it's suppose to, it only drops the idle way down. I replaced the EGR valve and still the same thing. I kept going through the check list and on the vacuum line between the air chamber and the EGR control solenoid valve I should have "approx 8 inch of vacuum" I only have 5 inch of vacuum. Everything else checks ok. the solenoid clicks when I jump it and all the voltages are correct. If anyone has a suggestion it would be great. I need to get this to work to pass emissions.