My 93 Accord was throwing a Code 12 (EGR - Lift Valve Sensor). Taking a gamble and going on a hunch, I removed the EGR valve, cleaned outthe gunked carbon inside theport, and thenput in a new EGR valve.

Afterresetting the ECU, I took it out on a test drive and the CEL still came on for Code 12.Can anyone give me some ideas what can be the problem?

Note: Though the EGR valve replacement didn't kill the CEL, I did notice an improvement in performance. Also, the CEL takes longer to come on after I replaced the valve....within 30 minutes now compared to within 10 minutes before.

 

you need to check for vacum to the EGR valve when you have a warmed up engine and RPM is raised up around 1700rpms.
The lift sensor throws the code if the valve isn't opened up as much as it should be.
I've just recovered from a major computer crash, but will repost if I can find that diagnostic chart.