Daughter has 97 Altima 4 cylinder. She's been driving it for about 6 months now since I bought and resurected it from a neighbor that had it sitting for about a year and a half. Failed emissions. Codes are P0325 Knock sensor,P0335 crankshaft position sensor, P1336 manufacturers code. They also noted the check engine light does not work. (Probably first time someone has complained about that.) Anyway before spending money for the knock sensor, can I test it with a meter? I'm thinking the knock sensor code is causing the crank sensor code. Has anyone ever heard of the check engine light not working. Doesn't it usually come on when you first turn the key? I guess it could be the bulb but what are the chances of that? She doesn't have a lot of money, so we don't want to waste it on something that won't fix it. Car runs fine. Don't know if this has anything to do with it, but her brakes seam to be going into antilock mode once in a while when braking. Any input would be appreciated. Thanks.