Like the others here have said, SCGT
, the most common cause is typically a "noisy" electrical system, which, upon the vehicle going WOT, the phenomenon is exacerbated.
Nothing more mysterious or cryptic. Yes, it's just that simple.
On older vehicles, contacts which have loosened or become corroded or otherwise degraded over time can be a big cause of such noise. If your older vehicle's charging system has itself been ruled-out as a potential cause (either lower-than-acceptable or higher-than-acceptable threshold voltage values can cause this kind of behavior to happen, with modern detectors), then it's time to start tracking down the specifics. Start with the easy stuff, first, such as making sure that your hardwiring is sound and/or the cigarette-lighter/12V-accessory socket is still good-to-go (this includes not only making sure that the socket itself is clean and can provide good electrical contact to your detector's power plug, but also checking the BACK SIDE of the socket, both the immediate hardware (which can loosen or degrade over time) as well as its upstream wiring. In some older, road-weary vehicles, a detector's sensitivity to such electrical noise has even been the tell-tale that allowed, finally, their owner to realize that more extensive problems, such as the need to re-do the engine-bay main wiring harness grounds, etc., is the actual cause.
On newer vehicles, simple individual/unique unit build-variation can often induce electrical noise - but yes, some vehicles (such as modern force-fed Subarus, out of all things!) can have a "tendency" towards such traits, too. Oftentimes, just an in-line, clip-on, Ferrite choke can do wonders, but in some cases, more extensive troubleshooting and methods may need to be undertaken. I would, no matter what, truly reserve "sending the detector back to the manufacturer" to get "fixed" for this problem as a last-resort measure, as not-infrequently, such fixes may involve increasing shielding around the laser-sensor, and as a by-product, may itself decrease laser sensitivity. [ Example: A good friend of mine in the NE states also drives the same kind of car as I do, the same year-of-manufacture, no less - his late-year, 2007, Escort 9500i would persistently false laser in his vehicle, at WOT, and he tried *everything* to cure the issue, himself. He finally had to send the unit back to Escort, who told him that they will increase shielding around his laser sensor, but that he'd lose about 30% of his current laser sensitivity
As a part of troubleshooting of modern vehicles, one must also take into account the multitude of electronics - both factory as well as aftermarket - that are present in our cars.
It has been well-documented that many such electronics can cause a detector's laser-detection circuitry/optics to think that it's actually seeing a valid laser hit. For example, many vehicle's factory navigation screen often cause such interference, and aftermarket screens for the same, as well as for things like carputers, etc., can also cause issues.
Regardless, these instances are both well-known as well as have dedicated solutions within the hobbyist community. Again, I will refer you to the RadarDetector.net database for such: Things that give false laser alerts - Radar Detector Jammer Forum
^ This thread describes, in varying detail, some of the most likely causes of such falsing. This is what I consider on the order of "basic knowledge and know-how" for any advanced detector user, and I would highly recommend that you read through this thread, and take notes.
Although this thread lacks direct reference to first-hand incidences of such falsing taking place, trust me, SCGT
, when I say that each of the examples logged have seen MANY case-reports in the community (for example, the latest "re-discovery" was that of the factory nav-screen being the cause of some user's woes), and all are "real," unlike the theory proposed by your cited fellow car-lover, above. possible cure for x50 false laser alerts - Radar Detector Jammer Forum
^ The above is a thread which explores many of the troubleshooting options in-detail.
[ Note - Yes, on some detectors you can turn off a certain alert "band." However, even on the ones where you can disable the laser alert, it is not unheard of for such falsing to PERSIST, even after that "band" has been deactivated.