How to change a knock sensor 2003 Mazda Protege

[kariwojo]

My check engine light for my 2003 Mazda Protege comes on in the rain. We checked the code and it says it is the knock sensor. How do we get to it? It seems like we'd have to take off the intake manifold to get to it? Does anyone have a diagram? Can you get to it from underneath the motor? Any ideas as to why it only has problems when it's wet out?

 

[clement_ghost]

Probably the sensor itself is cracked and when it gets wet, sensor becomes defective.

You can change it from underneath. It's just threaded on the engine block, nothing will spill from it when you get it out.

 

[dmention7]

Pulling the intake manifold will definitely help get access to the sensor, but yes you should be able to get to it from underneath the car.

The fact that the CEL only comes on when its raining could be due to water getting into the connector plug as well. I've never heard of that specifically happening on a protege, but it is a common issue on the suzuki sx4.

That said, the knock sensor is not really doing anything except for perhaps pulling some ignition timing if knock/predetonation is occurring (pretty uncommon in general) As long as you're not using terrible gas, and the rest of the engine is in decent shape mechanically, there is no great need to replace the sensor since it is presumably functioning okay except for when it gets wet.