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Shudder

I have a 2002 Mercury Sable. When cruising easily and the transmittion shifts, a shudder occurs when giving just a little bit of fuel. The shudder goes away when given more fuel and when the transmittion changes gear. I had the transmittion filter replaced and the mechanic checked it with a computer and P1401 came up. Could differential pressure feedback EGR Circuit High Input be the problem?

It is possible. A problem in the EGR system can cause all sorts of different kinds of driveability problems. It is also the case that failure of the DPFE sensor is pretty common, and you are going to need to get it fixed either way. Because of the problems Ford has had with the DPFE sensors I’d be willing to bet that the sensor itself will end up being the problem. There is a diagnostic procedure that ought to be done though as the EGR system includes the EGR valve itself, a solenoid & this sensor. Lots of parts end up getting thrown at these because they aren’t diagnosed first.

The let down, though, is that I don’t know the proper testing procedure - but I’ll bet someone else here can tell you what to do.

The other let down might be that this isn’t your shudder problem - maybe, maybe not.