My check engine light was on and had 2 codes one was a knock sensor code and the other was a P1400 i changed the knock sensor (and by the way it was bad cause the plastic that goes around the metal part was cracked ) and cleared the ECM and drove around for about a week with no CEL but now it has come back on again but the knock sensor code is gone but the P1400 is back what is this code and has anyone experienced this or has a fix for it ?

 

By the way I have a 96 5 speed SE

 

P1400 code is a EGR sensor valve faulty or circuit faulty.

You said that you have changed your Knock sensor recently. Look if you don't have some hoses not connected or loose or cracked.

I dunno if you have some equipement at home but if you have a vaccum pump you can start the engine, remove the vaccum tube on top of the EGR valve and apply some vaccum on it when the car is at idle. If you can apply some vaccum on the EGR valve, you will see that the motor will begin to have difficulty to idle correctly. Look if your vaccum pump keep his pressure too.

If it does nothing, your EGR valve is clogged or the inside of the valve is broke.

If you don't have some tools at home or you don't know about mechanic, get the book for your car and start learning about that or get your car at a good mechanic you know.
Good luck friend!