Several miles down the road after fueling my tank the "check engine" light came on. The code is 0401. I had the egr valve replaced last year so I can't imagine that it needs to be replaced so soon. I was told that there may have been something in the fuel to muck up the line. I have no technical capability, so am dependent on having a mechanic fix whatever is wrong. Any suggestions other than an expensive cleaning?

 

OBD-II Trouble Code: P0401 Insufficient EGR Flow

 

now, not to be a *****... if you have ANY technical knowledge and basic tools, remove EGR valve, and spray clean it with carb cleaner. check for any damaged vacuum line going to it.
on a philosophical note, buying cheap gas never helps. only gumms up everything and costs repair money down the road.

 

The link will provide info on how the system works.

http://www.autoshop101.com/forms/h61.pdf

 

You say you have no technical capability, so I don't know if providing more technical documentation will help...but I really found this series of articles from Motor Magazine helpful for diagnosing my problem (mine was the VSV).

MOTOR Magazine Article | MOTOR Information Systems (August 2009)
MOTOR Magazine Article | MOTOR Information Systems (September 2009)
MOTOR Magazine Article | MOTOR Information Systems (October 2009)
MOTOR Magazine Article | MOTOR Information Systems (November 2009)
MOTOR Magazine Article | MOTOR Information Systems (December 2009)

You can download each article as a PDF, and they all include pictures.

If you want to run some tests yourself, you can rent a vacuum pump from Autozone and pull/check vacuum at various places. Once you have the vacuum pump, checking the EGR valve itself is very easy (start car, take hose off of top of EGR valve, pull vacuum on the EGR valve, car should stall). The only problem I ran into checking various components was that the hose to my vacuum pump was much larger than Toyota's hoses and fittings. I solved this by getting out some teflon tape (like you use in plumbing) and carefully wrapping it around the various fittings to make them much larger and more air tight. Worked like a charm. In 15 minutes, I was able to rule out the EGR and the vacuum modulator, which meant that it had to be the VSV (or one of the hoses going to/from the VSV).

 

I stopped by my mechanic to ask his opinion (since the valve was replaced in July). He suggested that it wasnt' "bad gas" but could be the "hose" so he will check it when I take it in. I appreciate all of the "technical" solutions, but they were too complicated for me.