I had the same issue as macao. Most of the forums don't mention the thermal breakers in the probe circuit. Here's a detailed troubleshooting description.

OK - here's a little tip that might save you a bundle of cash:

The Frigidaire glasstop slide-in Range model # PLES389ECH has a habit of triggering a F30 error, which according to the NEW table of error codes (http://www.applianceaid.com/faultcodes3.html), implies an issue with either the Electronic Oven Control (EOC) panel (located beneath the Control Panel Assembly), or the temperature probe itself (located within the main oven cavity, back wall, upper-left corner). However, a quick glance at page 12 of the Factory Parts Catalog's wiring diagram (http://www.youserguide.com/wiki/Frigidaire_PLES389ECH or http://www.serviexcell.com.mx/manuales/PLES389ECH.pdf) shows two thermal breakers wired into the circuit as well.

To check the probe, disconnect power and either pull the probe from the cavity of the oven (two screws, and a disconnect plug) and measure resistance across the probe, or take the Control Panel Assembly off the front (remove 4 cooktop control knobs and 4 teflon mounting nuts) and measure resistance at the EOC P5 quick-disconnect plug (violet wires - see wiring diagram)...it should read approx. 1091 Ohms at room temperature per ApplianceAid's table. If you measured at the probe, an open (infinite resistance) or short (zero resistance) indicates a bad probe. Replace for about $40.00 (per http://www.appliancepartspros.com/partsearch/model.aspx?model_id=5160618).

If you get an open or short by measuring at the P5 plug, the issue is either the probe OR the thermal breakers. Also called a Thermal Cutout Switch (item #141 on p.8 of your parts catalog), one of these buggers is located near the electronic control module for the right rear stovetop burner (#54A, follow the violet wires from EOC to locate it) - since you already have the Control Panel Assembly pulled, reach over and push the button on the breaker to reset it. This may have just solved your error code! For FREE!! If it doesn't reset, you may have to replace the breaker itself (around $16.00).

However, if you measured at the plug and get the appropriate resistance for the entire circuit it's likely that your breakers, probe and wiring harness (always check for disconnected wiring) are fine, and that the problem lies with the EOC itself. This pricey gizmo runs a little over $200, but it's easy to change. My sympathies.

Good luck! Feel free to mail me any contributions should you save yourself a $350+ service call. :)

Thank you very much Frydman.
Only thing to add is that the thermal breakers can have an intermittent issue (probably with reset (red) switch). Of course this makes trouble shooting a little more challenging and you are better off replacing one if it even seems to give you an issue.
Taking a good look at a CORRECT wiring diagram is always a very good idea!