Immediately after starting microwave, it will stop and have to be completely reset, then the same thing happens again. A day or so earlier, I got a "sensor error" reading in the display screen.

Sadly, we hear of this over and over.

This is due to a defective or loose magnetron causing electrical interference and disruption in the control circuit board.

If your magnetron was recently replaced, it may have loose mounting nuts or bolts or maybe the wire mesh RF gasket was not installed or got pinched.

It may also need a new high-voltage diode and stirrer, and the cavity may be affected.

Details are in their bulletin here. Even if your model is not on the list, the same problem can occur, requiring a kit. The parts kit is similar to this one.

(Your model may use a different kit - this is shown for illustration purposes only).

If you or someone you know decide to look into it, we have critical information on safety, disassembly and door switches at our site, and our link is at our listing here on FixYa.

There should also be a "mini-manual" hidden inside the unit behind the control panel or hidden on the left side behind the grille, which is very helpful when troubleshooting.

You can find helpful exploded view diagrams and order parts by entering your full model number here.

If it's within the magnetron portion of the warranty (usually 5-9 years) but out of the original full warranty (usually 1 year), then your manufacturer will cover the part cost, but not the cost to visit you or the labor charge to do the work.

They may even send you a replacement magnetron. GE Customer Service is here.

We're happy to help you and we'd appreciate your thoughtful rating of our answer.