Rough Idle and EGR P0401 Issue - Toyota Nation Forum : Toyota Car and Truck Forums

rpk1974 · 10-04-2010, 02:38 AM

I received a P0401 code from my 2001 Toyota Camry. I'm going to follow the steps given in this post to diagnose and fix the issue.

Symptoms are rough idling and poor acceleration every few minutes.

From what I've read, I'm guessing the EGR Valve is blocked with carbon build up, but I'm not quite sure if that's the the only culprit. I think I may be having issues with the vacuum switching valve too, but I don't know how it operates when it's working or not. What are some signs of a bad vacuum switching valve? I disconnected its hose from the EGR Valve to test for suction and felt nothing.

Nervous · 10-04-2010, 07:33 AM

Some info is here:
DIY: 1MZ, EGR, code P0401 & P0402 diagnostic & repair

Pay attention to PDFs, the links in the first post.

**TOYOPARTSMAN** · 10-04-2010, 07:37 AM

There are other thread in the forum for this very issue. The EGR valve (25620-74330) is probably full of carbon and you can start by removing it and cleaning it. When you do, make sure you get new gaskets. the next part is the EGR modulator (25870-74090), It is connect to the EGR vavle and is round and has a white filter inside. You can try to remove that filter and clean it and reassemble it. The last part is the EGR VSV (25860-74050) and it is either good or bad. If it is bad, you'll need to replace it.

The EGR Valve and modulator if you cannot clean them sufficiently, they may need to be replaced.

I did send you some information regarding this.

Good luck