Ive bought a couple of the Advance units, one was dead right out of the box, other lasted a couple months. Took them both to Autozone to test them and they both failed and past, tested them both several times. I just bought one from NAPA and has worked so far. I took the NAPA unit to autozone to test it and never failed, tested it 4 times. Seems like its really a crapshoot as to whether or not you get a good one. HTH Deren