P0401 code help needed

Thanks RJParker for the better picture of the VIN plate on the engine. That EGR schematic is of great help. I'll need to bring out my multimeter and test for continuity. Visually everything looks good but wiring seems to be the only thing I haven't really checked out yet to determine whether the EGR valve is getting the power it needs to open and close the valve. Thanks for the great recommendation. I have been trying to get the EGR step test done but my Techstream keeps crashing! Need to find a more stable version. Currently using version 13.00.022.

 

You're right it that it is a tight fit. I do have an endoscope camera that I can attempt to snake back there to try and make out the numbers. Otherwise, I have an oil change to do very soon so I will check it from under the car if the scope doesn't hack it.

 

Gosh, I am learning so much from this forum. I didn't know salvage yards were allowed to remove the VIN plates. It seems to me like filing off a serial number of a gun so that it becomes untraceable. So sad!

 

Thanks for your wisdom. I will double back and recheck throughout the system. Yes, I have acquired a stable version of Techstream and will try to command the EGR valve position. Will report back.

 

Mendel, EGR valve in the car is new and shiny. Come to think of it, the only thing I have not determined is whether this is an OEM part or cheap aftermarket. I don't have the car with me at the moment to be able to verify this. If this is an aftermarket part, it could explain why this EGR valve may not be working properly and causing an P0401 code to pop up. I guess I can't assume brand new parts are guaranteed to work 100% especially if it is a cheap aftermarket replacement.

 

Mendel, I bought this 2010 Prius about 3 weeks ago at 208K miles for my son. The previous owner already had this EGR valve installed. He owned this car for 3 years and drove it only for about 12,000 miles. He had told me that he had a check engine light (P0401) turn on and off intermittently during his ownership. I am the third owner of this car. In my mind this would be an easy fix by just cleaning out the EGR cooler, EGR pipe, and intake manifold. After all this, still looking for a solution. Still need to check the circuitry of the EGR valve, whether the EGR valve is OEM or aftermarket. Problem is my son works nights so when I get home I don't see the car until early morning when I leave for work. Not really enough time to work on it to do diagnostics.

 

I confirm that it's an aftermarket EGR valve that is made in China. There are no markings in the area where there should be a part number. This could very well be the cause of my P0401 problem. Thankfully, the previous owner left me with the original EGR. I will open it, clean it up thoroughly and make sure the valve is opening and closing properly. I will then put this original one back to see if it works. If it doesn't work, I will need to purchase one.

 

Sound like a plan! I am going to cross my fingers and hope I can still get some life out of it.

 

Over the weekend, I was able to get an used updated EGR valve (part no. 2562037120) from a salvage yard. I cleaned it out the best I could and replaced the "new aftermarket Chinese-made EGR valve" that was previously installed. After a few test drives I am happy to report to @ChapmanF that my readings are now within normal limits (see pic below) and no longer getting a P0401 code. To summarize, the original OEM EGR valve failed. The previous owner had it replaced with a cheap aftermarket before selling it to me. He did not disclose to me that this was an aftermarket replacement so all the while I thought it was OEM and didn't realize it until I posted this thread. Thanks for those who shared their opinions! The lesson here is always replace with OEM, especially with an EGR valve.