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Ron Stygar Carl Buckland Dale Beuning Forums Help

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Subject: <E34> OBC Outside Air Temperature Reading

> My OAT reading went to -35 degrees F yesterday and
> stayed there. I checked the wires and reseated the
> connector at the probe and the went up to -17, but
> that's it. This morning it read an accurate 34 degrees at
> startup but quickly returned to -35.

> Does anyone know the typical failure mode for the probe?
> Any other ideas?


> Joe

Joe, I had the same problem. before you go out and purchase a new sensor take an ohm meter and check the continuity from one side of the sensor to the other. If continuity is good the sensor should be fine. I would say that you have a bad connection to the sensor or a wire short. remember you moved the cable around and pushed the plugs back in and the sensor worked for a short time but then whent back to -35. Check your connections and wiring thats the problem. Also, sensor does take 24 to 48 hours to reset.

If the obc reading keeps going to -35f then you need a new temp. sensor. The older version used to go to -22f when they broke but the new ones kick out at -35f. Change it and allow some time for the obc to readjust.

The problem was a broken wire in the 2-wire bundle leading to the sensor. The bundle had been chafing against something behind the air dam and had worn through the outer sheath and one of the wires. One crimp connector, some electrical tape, and five minutes later, the system is back to normal.

Thanks for all the tips.

'90 535i(m) 189K+ miles and going strong...

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