Ona mission

I have a rough idea how the knock sensing system work but do they fail? My 04 coupe (no mods) seems to have a knock once in a while. I usually do keep high test in it but have heard a ping/knock under some situtions and at full load. No codes or Engine service light

thx in advance for the help.

3boystoys

They do fail and they do throw codes when they do, are you checking codes with the DIC or a handheld scanner?

They generally fails by water infiltration from the top (people washing their engine with water) or from below with oil (there are plastic caps in the bottom of the wells the sensors sit it and they leak).

Ona mission

With the DIC, I'll give the scanner a try when I get a chance but wouldn't that give a check engine light? thx

3boystoys

DIC is fine for this but a decent scanner will allow you to graph the output of the knock sensors and to capture them . The CEL would trigger if the sensor(s) were BAD, your's are most likely OK and the system may not be able to adjust the timing enough to compensate for bad fuel or excessive carbon buildup.

RonSSNova

The system can adjust enough. Just not fast enough.
They have to hear the knock first, then pull timing.