A computer diagnostic on my 1999 Honda Accord showed Code P1607 (ECM/PCM internal circuit failure. Would rebuilding the existing computer eliminate the Malfunction Indicator Lamp light from coming on whenever temperatures drop below 55°. Could there be an underlying problem, such as a bad alternator, etc. that is the cause of the MIL light to light up? Or, would the rebuilding of the car's computer correct the engine problem?
Thanks.

There's a high probability that an underlying problem shorted out the ECM. Did you:

. Jump the battery? Voltage spikes can damage the ECM, alternator, and sensors.

. Replace an alternator without removing the negative battery cable first?

. Splice wires or work on the electrical system without disconnecting the negative battery cable first?

. Allow the car to go through high water?

If none of the above happened, I would have your current ECM rebuilt, especially if you have an immobilizer system.