I read recently, that P0401 code can be caused by a slightly worn valve.

Question

It said that someimes replacement with a new EGR valve, does not always remove the reocuring code default because the worn valve gives the PCM a different reading each time. To clear this memory out of the PCM without a dealer flash, it said next time the code P0401 comes up, befor running a code scanner and erasing the code, just shut the car off, disconnect the wiring connection on the EGR valve. Turn the switch on, and scan the code and clear the code. As soon as the code cleas, turn the switch off. Then reconnect the wire connection to the EGR. Then start the car. This supposedly clears the memory for a new point in the PCM. Is this valid?

Answer 1

P0401 EGR flow insufficient

The PCM allows 9 to 12 flow sample to be taken during a ignition cycle,During this time it can determine whether the EGR passage is plugged or the EGR is non operational.If the intake valve are worn the intake is late and the exhaust closes early, You would code up a running rich condition.The PCM looks for open shorts, grounds, rationality and irrationality so this method is non valid