P0401/P0402 Codes - Help needed

Hi All,

I have a '99 3.8L which I just recently performed the Isolator Bolt repair to fix the P0171/P0174 codes I was getting. The van ran great, with no CELs, for 3 days, then the CEL came back on with P0401/P0402 codes. I also just recently took the van on a long trip and my mpg greatly increased from 13 to 22 mpg highway. I'm still waiting to see what my city mpg turns out. I've heard that these codes can lead to the DPFE sensor. Today I drilled out the rivets and found that it was very clean inside with no broken wires or burned boards. There was only a little moisture on the round sensor part. I cleaned it up and put it back together with some sealant on the outside and two zip ties. Still waiting to see any change.

Does anyone have any suggestions/opinions/things to check next that could help my situation?

Thanks,
SMF

Hi All,

I have a '99 3.8L which I just recently performed the Isolator Bolt repair to fix the P0171/P0174 codes I was getting. The van ran great, with no CELs, for 3 days, then the CEL came back on with P0401/P0402 codes. I also just recently took the van on a long trip and my mpg greatly increased from 13 to 22 mpg highway. I'm still waiting to see what my city mpg turns out. I've heard that these codes can lead to the DPFE sensor. Today I drilled out the rivets and found that it was very clean inside with no broken wires or burned boards. There was only a little moisture on the round sensor part. I cleaned it up and put it back together with some sealant on the outside and two zip ties. Still waiting to see any change.

Does anyone have any suggestions/opinions/things to check next that could help my situation?

Thanks,
SMF


Replace it and check the hoses.
Also check dealer for updated sensor.
MT

Update,

I did a little troubleshooting and found a few things;

1) Removed EGR valve hose, plugged it and applied vacuum (human) to the valve. Car stalled as expected.
2) With KOEO, voltage measured at the DPFE sensor was 4.55 volts.
3) With KOER, voltage did not change but did change to ~4.8v when vacuum was applied to the DPFE intake hose and down to ~3.5v with postive pressure.

Seems like this is definitely pointing to the sensor. The dealership wanted $77+tax but Fordparts.com wanted ~$56+shipping.

smf

What part number are you getting? For mine, it was 4U7Z-9J460-AA. It's a small black box, mounted directly to the EGR pipe. It costs about $30.

For Motorcraft from a FORD dealer online parts department,
They have one at Millennium Ford in Seatle for about $56 from a list price of about $103.
http://www.trademotion.com/partlocator/index.cfm?siteid=214072
Under Mechanical Parts, select your year, etc....then...
Look under Emission System, EGR System, Pressure Sensor

For after market,
They have the Standard Motor Products brand, black case, at www.rockauto.com for about $55.
They also have Airtex for about $32 and True Tech for about $42, but I am not familiar with those brands....and they don't show a picture of them.

These prices are for 1999 (and some other years) 3.8L as of today.

The original DPFE sensor is the aluminum version p/n: F7UE-9J460-AA. The updated plastic version (I hope) from Ford is p/n: F77Z-9J460-AB. Mine is mounted with 2 bolts in front of the intake manifold with 2 hoses and connector. I'm going to see if my local Ford dealer will accept the online price. If not, I'll just order it from Fordparts.com or Millenium Ford(trademotion).