check engine light on questions?


New Member
Dec 23, 2003
I have the code reader and it pulled two codes from my 89gt mustang. The codes were 31 C and 31 O. Both of these codes mean EVP or PFE circuit below minimum voltage. What problems could this cause and how can I go about fixing the problem? Also I discovered that one of my vacuum lines has been destroyed. It is not the one that runs to the egr or the back of the intake though but it is bundled with those so what could that be and is it related to my check engine light coming on? Any help would be great.
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Mar 10, 2000
Dublin GA
CODE: 31 (KOEO) - EVP circuit below minimum voltage. Vref missing or broken wire or bad contact in circuit. Check for 5 volts on the orange/white wire. With the sensor removed from the EGR and still connected, press the plunger and watch the voltage change on the brown/lt green wire. Check for the same results on pin 27 on the computer.