Knock Sensor Question

[werepe]

hi guys,quick question: my friend's 93 Q45 has two cracked Knock Sensors. These sensors only have 55K miles on them and the plastic surroundings are cracked. Does the cracking mean they've gone bad or do they still function well eventhough they have cracks?Thanks!

[Q45tech]

When did he abuse the engine by overheating it? The early cause of cracking.

The plastic acts to confine the ceramic between the two metallic end plates.......cracked housings change the frequency response and amplitude sensitivity.

Usually ok until they throw the code.