will a bad knock sensor always throw out a code?
- Thread starter gpmarzan
- Start date
illGT4":1mxr9kfn said:
I just wanna know if it'll always show a code. i read somewhere here that a bad bad knock sensor made their car run like a slug, which is weird to know cause i thought knock sensors are there to listen to engine knocks and retards timing when knock is occuring to prevent your engine from damage. can there be a reason that a knock sensor gets too sensitive and tells the computer that there is knock even though there isnt? i dont know if im making sense. im typing this in a rush cause im trying to finish up my hw for my drafting class here at the school library.
I would imagine if your car went limp because of knock your going to have to clear the codes from the ecu before it will remove itself from the "safe" mode. If your knock sensor is bad then my guess would be yes it will always throw a code, because the engine will constantly think its getting knock. if it didnt work this way I would be shocked, because then how would you know the sensor is bad? and if you dont know the sensor is bad then you could very well destroy your engine, therefore negating the purpose of a knock sensor in the first place. I dont have any real proof on that, thats just my common sense speaking......
There are two types of failing knock sensors. Ones that detect false positives, and ones that detect nothing at all. The ones that detect false positives will throw a code. However it is similar to the overboost code. Once the ECU sees enough repetative knock it can somtimes "lock" you into low boost mode until you reset the ecu. However you should still be able to pull the old code until you reset the ecu. The other type of knock sensor failure is more dangerous as it will give you no warning as to if you're experiencing knock or not. The only way you'll know is when you blow a piston.