CEL & Code 31

[FoxRodStang]

What exactly does the code mean & what do I need to fix? The only info I can find online so far is "PFE or EVP circuit below minimum voltage of 0.24 volts." The only emissions equipment on my car is the egr. The TAB & TAD solenoids are still plugged in, but, no vacuum lines are connected to them. Nothing has been changed on the car in over a year, the CEL just came on recently. I don't remember if the code was present before the CEL or not.

Thanks!

Matt

[FoxRodStang]

anyone?

[Sphinxmunkey]

CODE: 31 (KOEO) - EVP circuit below minimum voltage. Vref (5 volt reference voltage supplied by the computer) missing or broken wire or bad connection in circuit. Use a DVM to check for 5 volts on the orange/white wire. If it is missing, look for +5 volts at the orange/white wire on the TPS or MAP sensor located on the firewall near the center of the car. Use the black/white wire for the ground for the DVM.
With the sensor removed from the EGR and still connected, press the plunger and watch the voltage change on the brown/lt green wire. Pull the passenger side kick panel and measure the voltage at the computer. You will need to remove the plastic cover over the wires and probe them from the backside. A safety pin may prove very useful for this task. Use pin 27, EVR input (brown/lt green wire) and pin 46, signal ground (black/white wire) to measure the voltage. The orange/white wire is Vref and should always be 5 volts -/+ .25 volt. Be sure to measure Vref at the EGR sensor to rule out any broken wires or bad connections.

And for credit, since I'm not a car genius I just know how to use yahoo... :) http://forums.stangnet.com/651919-limp-mode-cel.html

[Sphinxmunkey]

If the egr is removed and you're worried about the code, you take a yellow wiring cap, screw connector type, and it will hold the metal pushrod on the egr sensor halfway down so your car thinks its working...

There's better nfo on the corral, which I'll link you to if I can find it, and if you have the egr unit to take the piece off of to rig up. I did it on my 95, tucks away and hides behind the main wiring pretty well... had to get rid of my cel to sell/trade it :)

[FoxRodStang]

Thanks for the help y'all. I checked the egr position sensor with my dmm. It checked good - voltage swing was within spec etc. I checked all the wires, none broken, nicked, etc. So, I resulted to my least favorite method or repair - throw parts at it till it fixes it! $25 at NAPA later, I have a new sensor. Install, clear codes. 2 days later, still no CEL, thank God. Hopefully it stays fixed.