Running Rich, Can't figure it out, Please help me out! Code 42 all the time!

the nit would have to be a sensor of some sort i would think

Let us know if the new o2's solved your problem. I have similar symptons.

hey tim where exactly is that link?

Marginal ACT or ECT sensors can cause code 42.

Here's the ACT & ECT troubleshooting path:

Code 21 – ECT sensor out of range. Broken or damaged wiring, bad ECT sensor. Note that that if the outside air temp is below 50 degrees F that the test for the ECT can be in error.

The ACT & ECT have the same thermistor, so the table values are the same

ACT & ECT test data:

Use Pin 46 on the computer for ground for both ECT & ACT to get most accurate readings.

Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts

Pin 25 on the computer - ACT signal in. at 50 degrees F it should be 3.5 volts. It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower intake manifold, the voltage readings will be lower because of the heat transfer.

Voltages may be measured across the ECT/ACT by probing the connector from the rear. Use care in doing it so that you don't damage the wiring or connector.

Here's the table :

68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61

Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.
50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms

93 teal terror said:

hey tim where exactly is that link?

Click to expand...

it is right by the windsheild wiper motor in that mess of wire. its a large blue wire with a black piece of plastic about an inch long and about 1/2 inch in diameter. the plastic part is the fusible link part. believe it or not on my 86 is actualy killed the og lights when it blew/ leave it to ford to put the fog lights and o2 sensors in the same friggin circut

thanx tim i did find it but it was a fat blue wire that turned into a red/green wire. The fusable link on mine is probably 2 inches long and only a little wider than the wire itself. How might I go about replacing something like that? I havent checked it yet but as soon as i get my hands on a voltmeter i will

just cut the old one out and splice the new one in with insulated connectors OR solder and heat shrink wrap it (the better alternative)

hmmmm you think Advance auto or auto zone would have one? Or is it a ford replacement part only?

NM...Ill just go ask around and see who has a 20GA fusable link. It says thats what it is on it. Doh.

you can get one at any parts place the color of the original wire reflects the amperage that you need, although i am not sure what amperage blue means (forgot) just get a blue link

awesome...great to see we actually know what we are talking about sometimes