My E550 Beltronics detector has developed a problem. When you switch it on it goes through its test sequence and seems to work okay but after 2 to 3mins it starts giving an audio alarm and the display flashes alternatively showing ; " ?LO3 CAL " and " MARKERS " this goes on continually and has to be switched off. Please advise if you can.

SOURCE: Beltronics Vector 985

If its still under warrenty Call Beltronics 800-341-2288 I had the same problem and they re-tuned the Detector and updated the firmware my Vector 985 was out of warrenty by 5 months and Bel repaired it for free. Hope this helps

SOURCE: need manual for beltronics radar detector 965

see the manual or the sticker on the device, somwtimes website are printed in there and try to search the website.

SOURCE: BELTRONICS 940

This is a somewhat common problem that occurs when a strong voltage spike while starting your car damages the radar detector. Bel can fix your RD. Once you get it back, always start your car first before powering on your radar detector. Likewise, power off your radar detector before turning off your car's ignition.

SOURCE: Beltronics radar detector gives constant alert after startup.

This is caused by the RD's local oscillator becoming unstable at higher temperatures due to a component which has become defective. Since this is an older radar detector model, you will have to pay a service charge to have it fixed. On the other hand, perhaps it is time to upgrade your remote installation to either the Escort 9500ci or the Bel STi-R setups? These newer models from Bel/Escort provide much better performance.

SOURCE: Vector 940 works for a moment, then flashes ?L03 CAL ?MARKERS

just turn off the sws messages.
it probably recieved a jumbled signal from a "roadworks traffic control unit".that it couldn't understand.