Code # 0401

[jasonbrodsky]

Originally Posted by Mr_Bentwrench Disconnect D.P.F. EGR sensor. Key on, engine off. Measure voltage between the sensor VREF circuit and SIG RTN circuit at the D.P.F. EGR sensor vehicle harness connector. Is VREF voltage between 4.0 and 6.0 volts? if the connector has these values when unplugged from dpfe sensor the dpfe sensor is bad. which would be the same as unplugging sensor and seeing if code P0402 excess flow it tripped. I am having problems with the same trouble codes and have centered it to the DPFE. I have a 2001 F150. I have tried the test with a volt meter by back probing the electrical connection which is still connected to the DPFE and still has vacuum lines attached to it. Is this the correct procedure? The reason I ask is when the motor was cold and I had probes attached to the ground and the singal wire on the sensor connection I had 4.9 volts. When the motor was warm the volts never changed. Am I probing the correct wires? There are 3, signal ground and ref. Which wires should I prob? Thank you for your help?

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[wizkid1358]

I would go to the parts store and get new gaskets for the throttle body and intake adapter and see if the egr ports are clogged or not. This may save you alot of headaches and money. Just because the voltage isn't changing doesn't mean the sensor is bad, it may just mean it is not sensing anything different because the ports are completely clogged with carbon.

[SaintStephen]

I replaced my dpfe 1.5 years ago from kragen (they had one) instead of ford (didn't have one) in order to pass smog. It worked, but on my trip out to PA the last four days, it has been firing the 0401 code whenever I restart the truck (except a few times when it was pretty hot). I have been waiting for the kragen version to fail, guess it waited till I would be out of california :^). Off to find a Ford dealer locally.

cheers

[glc]

You can order a Motorcraft DPFE from rockauto.com.

[RONinTORONTO]

Thank you wizkid1358! I went to the Tomco website and read the tech tips. The plastic bodied and metal bodied DPFEs both have linear outputs, but they have different slopes. The plastic one produces 1 volt at 0 pressure difference, while the metal one produces less than 0.5 volt for the same difference. When the computer compares the voltage output to it's stored expected value at a given pressure difference, it won't match and an "insufficient EGR flow" code results. So a vehicle that originally had a metal one should get a metal one as a replacement.

[RONinTORONTO]

Originally Posted by wizkid1358

I know this is an old thread, but if your truck has an aluminum sensor, only use the Aluminum one (Tomco or motorcraft). The new plastic ones may appear better but they use different technology and put out a different signal voltage which is lower than the good ones which will cause the code to come up again. For me I bought the truck used ('97 f150 4x4 4.6L VIN code 6) and it came with the plastic sensor and had the EGR insufficient code, so I went Autozone and bought the sensor but still had the code. I have now completely replaced the EGR system (EVR, EGR Valve, tube, vacuum line, and hoses going to the sensor) and still have the code. Bought the Tomco 10906 and that solved the problem.

I just received a Tomco 10906 and it is plastic! I measured the voltage out (top pin) to ground (middle pin) with zero pressure differential. I read 1.0 volts, which is correct according to Tomco techtips issue 35. The plastic one on the truck now only reads 0.2 volts with zero pressure difference. (way out of spec). I checked with a FORD dealer and they had a plastic one in stock as well! I'll give the new Tomco plastic one a try and see what happens. By the way, the metal body one only puts out 0.5 volts at zero pressure difference according to Tomco.