My 1993 "P" series engine C4 has code 43 knock sensor code causing an erratic (sometimes on, sometimes off) check engine light. I've been told that changing the fuel filter could possibly help. I'll try that since the previous owner says it's not been changed since 2001. I got the car in March of this year; it now has 100,123 miles on it. My question is this: Are there two knock sensors, and do they screw into the water jacket? My shop manual isn't clear on the subject; one place shows two and another only one. I've read in some forums where the sensor does go through the water jacket, but the shop manual isn't clear on that either. Car has a Vortech supercharger, Borla exhaust, and the big K&N air filter. Anybody help me on this one?

Does it mainly happen in the morning!If it does scan the engine and see if you have knock signals on both sensors,if you do not have a scanner take My word on it that replaceing both knock sensor harnesses will fix it.You can get them with connector individually from the dealer. Good Luck