hi, I have a 98 toyota RAV4 and it displayed p0401 code. I replaced the EGR valve & erased the code. 10 mins later the same code is back on again w/ check engine light displaying. can anyone please help me & let me know what else I need to fix? thank you.
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1998 Toyota RAV4 Question: p0401
patrick mannion from Greg Solow's Engine Room, July 31, 2009, 03:14Master
The EGR system requires two trips to set a trouble code usually, when the computer is doing a monitor check. The vacuum switching valve (VSV) is a more common failure than the EGR valve itself. The VSV frequently fails intermittently. Look at the vacuum hose routing under the hood ensure vacuum hoses are routed correctly.
For an over view of the Toyota EGR system check out
I just tried this link but it did not work perhaps his site is down right now but I just looked at it a few days ago.
Answer #2backyard tech July 31, 2009, 09:38Master
This is where it is important to remember. How much money do you want to spend on guessing before you take it to a ASE certified tech? AUTOTECHPAT is correct. Most likely it is the VSV.