1999 Century EGR valve problem

[itsjustme100]

Looking for any help out there. My Service Engine light came on. The computer at the Service Station said it was the EGR valve. I've replaced the EGR valve myself (simple job), but the Servive Engine light's still on! Does it need to be reset, and if so, how... or is there possibly another problem?

I haven't run the engine very long since replacing. Also wondering if it will just correct itself after it's run for some period.

Anyone's expertise will be greatly appreciated. Thanks! Robert

[GTP Dad]

Welcome to AF!!

The light will need to be reset with a scanner. This code will not clear itself unfortunately. One item to check if you clear it and it does not go off is the passageway from the engine to the EGR. Sometimes they become clogged and will not allow proper flow. If the code goes away once cleared then you repaired the problem.

[jwichman]

I had a similar problem with my 2000 century, replaced the egr valve and reset the SES light. Ran good for about two months and then reset the code and SES. Found that the EGR passageway was completely plugged with carbon. Took a couple of hours, a brass tooth brush (from gun cleaning kit) and some carb cleaner spray to unplug it. Been great ever since.

[itsjustme100]

Thanks for the help. So, I've replaced the EGR valve. I pulled the EGR tube to check for airflow restriction. It was clear, no problem. Reinstalled, finally got the SES light reset, and it came back on that day. From what I've been able to research, it may be the DPF sensor? Is that the same thing as the O2 sensor? Is there anything else that may be causing the SES light to come on? The code off the ODB scanner was P0401, indicating: Insufficient EGR flow. Again, I really appreciate the help. Thanks again.

[BNaylor]

The PCM module tests EGR flow periodically using engine vacuum and manifold absolute pressure (MAP). Also, other engine parameters must be correct.

Check to make sure you have no vacuum leaks at the throttle body and around the upper/lower intake manifold. Make sure the PCV vlave is good and the vacuum line to it is good. Check the vacuum lines at the MAP sensor located behind the upper intake manifold.

You might consider running an engine vacuum test to make sure it is in specs. In a worse case scenario you could have the start of the classic lower intake manifold gasket problem which is common on a 3100 SFI engine.

[ed2903]

I had a similar problem with my 98 century. The problem was that the passageway from the intake to the egr valve was completely plugged with carbon. I had to remove the throttle body to get to the passageway. The opening is about the size of a pencil on the lower right hand side.