EGR Problems....

I have a 2001 tacoma 2.7 crew cab and I have changed the plugs, new egr valve, and gas cap and my truck is still throwing p401 code. I can still tell its using a littl more gas than it should what else could possible be throwing the same code?

 

I get an occasional 401 code in my 2.7, so I thought I would share my experience. You may not have the same problem

When the 401 code is active, I get no other symptoms. Runs great, and I get 20 to 24 mpg.

I tested the valve and it worked fine, so that wasn't it.
I replaced the modulator with a used one, and that didn't fix it.
I removed and cleaned the EGR temp sensor and that fixed it for about 8 months. Removed and cleaned again, and that had the same effect.

A permanent fix would be to replace the sensor, but its rather expensive, so I just clean it, occasionally.

The only other EGR component is a switching valve underneath the throttle body. Kinda hard to get at. Its got wires and hoses connected to it. You could check the hoses and wires going to and from that for any problems.

Good Luck