I've got an idea to allow bypassing the DPFE sensor so the MIL light doesn't come on and code P0401 or P0402 won't be set.
This would be an alternative to replacing a defective DPFE sensor if you know the rest of your EGR system is working ok.

Here's how it could work:

1. The concept is to make a little box that the DPFE harness would plug into (disconnectibg the DPFE altogether).

2. A tap from the EGR Vacuum Regulator control wire would also go into this box.

3. Now, inside the box is a relay that is controlled from the EGR Vacuum Regulator control tap brought in.

4. When the PCM activates the EGR Vacuum Regulator control solenoid, the relay in the box is activated and switches in a resistor combination that produces the voltage expected by the PCM.

5. When the EGR Vacuum Regulator control solenoid is turned off by the PCM, the relay would be off, switching in the resistor combination needed to produce the voltage the PCM is expecting in this state.

There are basically only two states that the DPFE is ever in:

1. Between .2 - 1.3 volts when the EGR vacuum regulator solenoid is OFF.

2. Greater than 4.0 volts when the EGR vacuum regulator is ON.

I think I can build this little DPFE bypass box for less than $15.

I have read that some people are having problems with the MIL light comming on and the DTC codes being set from bad DPFEs (my case) and some problems reported with exhaust mods. This box will not disable the functioning of your EGR system, it will just tell the PCM that everything is OK without needing a functioning DPFE.


It could also be used to determine if you do have a bad DPFE.
If you replace the DPFE with this box and the DTC codes go away you can assume the DPFE was bad (assuming you are sure everything else is good (EGR vavle, no plugged TB ports, etc.)

Any comments on the need for something like this?
If anyone thinks it would be worth it I'll make a prototype and post pictures and schematics in one of my photo galleries.
I might do it anyway just for fun.

 

The DPFE is used to tell the PCM how much Exhaust Gas is flowing to the intake manifold. Voltage will varry depending upon flow. Your box will still set codes.

Regards

Jean Marc Chartier

 

I stand corrected! :o

Thank you, JMC!

You are correct, the voltage IS variable and the EGR Vacuum Regulator is pulsed to provide variable vacuum to the EGR valve.

Please disregard the idea above - it wont work!