PO402 code

My check engine light was on so I put it on a computer which popped up po402 which is the egr. I replaced my egr valve with a brand new one and cleared the code. Well now my check engine light is back on and showing code PO402. I'm confused, anyone else have this problem and know what I should do? Thanks for any help!

 

There is a lot more to the EGR system than the valve. Different EGR codes mean different things.
Most people seem to do just what you did, guessing at it and replace the main valve, which is rarely the issue.
Other components are the modulator, vsv, temp sensor, and vacuum lines.

I had a p0401 code (insufficient EGR flow) a few years ago. I tested the valve, and it passed the tests. Then, I replaced the modulator (which controls the amount of flow) with a used one and that didn't help. Then I cleaned the EGR temp sensor (which actually measures the flow). That fixed it. If the problem comes up again, I'll replace it.

 

Thanks for the info! How did you clean it? Is it a lot of work to take on and off? The egr valve was a major headache to replace due to no room work with!

 

Easy to take off with the right tool. Its been a few years, but I think I used a special tool normally used to remove O2 sensors. Its a deep-socket (19mm maybe ?) with a slot in the side to allow for the pig-tail. At first, I used a solvent to clean it. But the code would come back after a few weeks. Then I used a screwdriver to scrape off the crusty build-up, followed by a solvent.

The sensor might not be your problem, but its worth a try.
Check all the vacuum hoses one at a time (carefully remove each one, inspect, re-install).
You can try replacing the modulator (flying-saucer-shaped thing on top). Easy to do.
If you get one from the wreckers, you'll save money.

The other piece is the computer-controlled VSV (vacuum switching valve). I have no experience with that.
There is a test for it in the FSM.