P1327 AND P0327 knock sensor

[RIboater2]

This is low signal to sensor 1 AND sensor 2 on bank 1. Since it's both sensors sharing the same connection plug I have to assume it's not the sensors themselves. The codes used to go away for a while if I unplugged them and wiggled the wires a bit but this no longer works. I also plugged in, but did not fully install, a new(used) set and get the same codes. So is it in the plug or somewhere else?

I also have a new code for O2 sensor 2 bank 1 no activity but doubt it's related since it's a new code.
I also can't seem to get my evap and oxygen monitors to be ready. Again probably not related.

[acspecialists]

Pull back the rubber covering the plug. I will probably find the wires are toast.
If you don't have INPA get it. You will be able to observe what is happening live and that will help immensely. For example if you have a vacuum leak and the car is running lean that may cause the knock sensors to go off.

[RIboater2]

I"m not with the car to look right now, but do you mean the male plug of the sensor harness, or the female plug of the wire harness? Keeping in mind, this is a V12 with a full harness case sitting above the intakes with 100 wires in it. I may have to trace the wires as far back as possible.
Just to clarify, the knock sensors aren't going off. there is no code for that. The code is for low input signal which I take to mean electrical

[Timm]

The error code means that the 'knock' signal from the cylinders is too low, it expects a signal as each cylinder fires whether knocking or not - and that usually means that the knock sensors are failing or incorrectly installed. Sticking one on the end of the harness will give the same code as it will not pick up the signal from each cylinder firing

[RIboater2]

Thanks Timm. I was afraid of that. I was able to use one from an E39 for $10 as the plug is the same, but the wires aren't long enough to actually install on M73. To get the correct one is $100 so I was hoping to test it first without pulling out the wire harness box and the intake manifold, which I believe is necessary to get to the sensors themselves. Big job for two small bolts
As much as I've done on this car, I've never had that harness and intakes out myself.
How do these sensors go bad? Other than wires aging? Can't be installed wrong as they are still factory installs.When I first started getting the code infrequently, I would tug on the wire to each sensor lightly and that would keep the code from popping.

[Timm]

They are similar to the PDC sensors being a piezo element, and just like the PDC sensors they fail on occasion through fracturing and (as seems to be your experience) the connections to the element fails. I mention bad installation as they can be destroyed if over-torqued....

[RIboater2]

Does it make sense for both sensors to go at the same time, but neither on bank 2? I can see one failing.

[Timm]

It does seem unlikely, but it is very difficult (if not impossible) to actually test the system without bolting them to the block!

[RIboater2]

Reporting back for others who may come up against this in a search. So in the end this was easier than expected. The codes are for low (electric) signal. Initially unplugging the tube like knock sensor plug and wiggling the wires plugging it back in kept the codes at bay for a while but each time it lasted less and less time. I'm now not sure that was actually doing anything or just coincidence. I decided to go beyond just that plug and traced the wires back through the loom into the fuse box where they plug into the ECM or DME? not sure which it is. I found some electric tape wrapped around the wires right at the hinged connector. I pulled the tape off expecting to find a splice and the source of the low electric signal. But there was none. Not sure what the tape was there for. I undid that connector and then put it all back together. Now I was getting code for only sensor 2. So on a hunch I just unplugged that connector again and pulled it on and off few times. Code for sensor 1 also now gone. Both codes gone for about two weeks now. Problem solved. I hope. Just not making good contact it would seem.