Q&A

It's the temp sensor in the EGR passage. Need to check it first.

Test the old sensor see if it has 8 to 10 mega Ohms resistance at 32 degrees, .6 to .7 mega Ohms at about 122 degrees , if it "open/no continuity the sensor is definitely bad. The sensor may be OK just not seeing exhaust flow across it due to a bad EGR valve or vacuum modulator. Alldata has easy to follow tests.
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First test the EGR system for malfunction. At 2500 rpm the valve should open, if not check for vacuum, if you have vacuum and the EGR opens, next check to see if the vehicle will stall when manually lifting the valve. if you stall, the system is good and poceed to testing the sensor. First check for an open circuit, then measure the resistance.