4AFE EGR Diagnosis

[RSTrider]

I have a question I'm hoping someone here can answer on how the ECM detects an EGR error (Code 71). From the documentation I can find, the computer looks for sufficient EGR temperature to verify the EGR is operating. Will the computer also throw a code if the EGR temp is hot when it shouldn't be? I'm having a hard time determining what is causing the code 71. All the components (balancing valve, EGR valve, VSV, vacuum ports, etc.) all seem to be operating normally. The temp sensor is new. Applying vacuum directly to the EGR valve will cause the idling engine to stumble or stall. The EGR valve leaks slightly (might be normal??) but the engine idles smoothly. The only thing that I can think of is that maybe the EGR valve leaks enough to let the temp sensor get hot when it shouldn't be, and sets a code. But again, nothing I've read suggests the computer looks for this. Will this set a code?

Thanks for your help.
Kevin

[SCT]

It looks like the temp. sensor will throw a code if it's not right somehow. I hope this helps and readable, they're from the factory service manual. The first shows the 71* error code, the second shows the procedures when testing the related stuff.