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There are sever things that can set this codes so lets start here.
incorrect installation of the Differential Pressure Feedback EGR (DPFE) sensor sense tubes from the Exhaust Gas Recirculation (EGR) delivery pipe Defective Differential Pressure Feedback EGR (DPFE) sensor
Monitor the output of the Differential Pressure Feedback EGR (DPFE) sensor signal circuit, Brown/Green, with a voltmeter, when opening the Exhaust Gas Recirculation (EGR) valve with the engine running. Voltage should start at 0.4 volts to 0.6 volts, when equipped with the oval aluminum sensor and 0.9 volts to 1.1 volts with the small square replacement sensor and smoothly increase as vacuum is applied to the EGR valve.
The Differential Pressure Feedback EGR (DPFE) sensor voltage should show 0.4-1.2 volts Key On, Engine Off (KOEO) and at idle, when the Exhaust Gas Recirculation (EGR) valve is opened with the engine running, the voltage should increase. If the voltage decreases, the sensors "sense" tubes are hooked up backwards. Looking at the Differential Pressure Feedback EGR (DPFE) sensor, the reference (REF) ports line should be connected to the delivery tubes pipe, which is closer to the Exhaust Gas Recirculation (EGR) valve than the exhaust manifold, and the HI port should be connected to the pipe which is closer to the exhaust manifold than the Exhaust Gas Recirculation (EGR) valve. The code will set when the sensor output voltage drops to 0.2 volts or less.
If I remove the plug connector, turn the key on, should I be reading any voltage at the connector, going to the brown/ green wire to ground? I am not reading any voltage at the connector doing this. Must engine be warmed up first or should I be seeing voltage there all the time.
Can I just use the battery ground which is close, and probe these wires at the connector and see what I have because I am not getting any voltage at any of these wires to ground or should I be doing this differently. It is unlikely that I would not see any voltage on any of the wires if it was a wire problem. am I right here or not
Enclosed is the scamatic for the PFE and you should be able to check Vref voltage on the same wire at the TP sensor.
Your very welcome. Its likely open in the harness someplace and yes some time can be a bear to find.