Vader GT

Hello folks just ran both tests above as my check engine light came on in my 1990. Got the following codes:

KOER
021 Engine Coolant Temp out of range

KOEO
031 EVP Sensor below min voltage

I did clear the codes, but know they will probably come back if I do not fix the root of the problem. I am not too worried about the 021 code as I did not let the car get too warm when I ran the tests. As an fyi....I just finished building the car (hds, cam, & it's had a blower on it for some time). It has NO egr stuff or polution items (smog pump, etc...) all those items are gone.

So the million dollar question is, how do I fix the KOEO code???

Thanks!!!

phoenix2121

Well your evap sensor is above your fuel tank normally. Your evap sensor could be bad. and with your coolant one your ECT sensor could be shorted just depends on what voltage it shows on a scanner.

dreamer1uk

The Fox Mustangs do not have EVAP sensors..

Code 31 is for your EGR and seeing as you have deleted it, there is a MIL eliminator kit available to fix that problem.

Code 21 for the ECT, you can test this easily with a DVOM and see if the resistance of the sensor changes as the temperature of your coolant increases. Simple test If the sensor is bad, you will see a decrease in fuel mileage. So at least give it a visual inspection, maybe do a voltage drop test to rule out any wiring issues on that circuit

dreamer1uk

This link will help on the EGR eliminators

http://rjminjectiontech.com/?p=9 Thank Tony71502 for the link.

Vader GT

Thanks you guys a ton, I took care of code 31 & now on to code 21 today, I love this place!!!

Joel5.0

Allow the engine to reach operating coolant temp (>160°F) .... and rerun the self test. If the coolant temp is below that value, code 21 will show up in a KOER self test but it doesn't mean you have anything to fix/replace..... just let it reach that temperature value and recheck.

Vader GT

Thanks again sir!!