Thank you for taking the time to read. I am looking for input on a persistent C5 knock sensor issue.

Car:
2000 Corvette C5, M6, ~148k miles, it does have a Z06 intake with the crossover cooling pipes intact. I have checked for pinched wires and I do not believe this is an issue at the moment.

Relevant current codes:

• P0327
  
• P0332
  
• P1637, generator L-terminal fault
  

Both knock sensor codes appear simultaneously. I have confirmed the P1637 appears to be an alternator/internal alternator issue. I do not know whether that could affect the PCM’s knock sensor diagnostics, but I currently suspect it is unrelated.

I had no knock sensor codes until I refreshed the top of the engine and replaced the original factory knock sensors.

Important note:
Every knock sensor install was torqued to 15 ft-lb. I verified torque with multiple tools, including a digital torque adapter. I do not see how I could be significantly off on torque, but I am still considering it as a possibility. I kept everything very clean during all work.

Timeline

At ~90k miles, I refreshed the top of the engine:

• Plugs and wires
  
• Top-end gaskets, including valley pan gasket
  
• Oil pressure sender
  
• Knock sensors
  
• Knock sensor harness
  

The replacement knock sensors were NTK/NGK units.

Shortly after that:

1. Rear knock sensor faulted.
   
2. Replaced it.
   
3. Later, front knock sensor faulted.
   
4. Contacted NTK and showed that the sensors had faulted.
   
5. NTK sent two replacements.
   
6. Installed one replacement.
   
7. System was fine for a while.
   
8. Rear sensor faulted again.
   
9. Replaced it.
   
10. It was good for about a year.
    
11. Rear started faulting again.
    

At this point, I had problems with 4 out of 5 NTK sensors.

Recent work

I tore everything apart again and replaced:

• Valley pan gasket
  
• Knock sensor lower seals
  
• Upper grommets
  
• Knock sensor harness
  

I then replaced the NTK sensors with Delphi sensors, hoping for a better result.

Result:

• P0327 and P0332 persisted.
  

I tested the sensors and wiring:

• Delphi sensors measured around 102k ohms
  
• Measured at PCM pins 11 and 51, I also saw about 102k ohms
  
• Based on that, I assumed the harness had continuity and no obvious open/short condition
  

PCM pins looked clean/new. No visible corrosion or damage.

I then reinstalled everything and ran the car. Codes returned.

I replaced one Delphi sensor with the one known-good NTK sensor. That code immediately went to history, which is what bothers me.

I then bought two GM Genuine knock sensors.

• GM sensors measured around 98k ohms
  
• Installed and torqued to 15 ft-lb
  
• Codes still showed current after install
  
• I reset the codes but have not yet fully run/drive-tested the car after reset
  

Current concern

The confusing part is that the one known-good NTK sensor appears to behave correctly, while:

• Multiple NTK sensors failed
  
• Two new Delphi sensors did not correct the issue
  
• Two new GM Genuine sensors have not immediately corrected it either
  

Since I can measure proper resistance at the PCM pins, I believe the PCM should be able to see the knock sensor circuits. That makes me think this may not be an open/short harness issue.

At this point, I am wondering if the issue could be mechanical coupling between the sensor and the block.

Possible next steps I am considering:

• Carefully clean the sensor mounting/mating surfaces with Scotch-Brite and electronics cleaner
  
• Verify the sensor bosses are clean, dry, and bare metal
  
• Reinstall sensors dry
  
• Retorque to 15 ft-lb
  
• Battery disconnect / PCM memory reset
  
• Retest
  

The only other thing I can think of is that I am somehow under-torquing the sensors, although I have verified torque multiple ways.

Any input from people who have dealt with stubborn P0327/P0332 issues on a C5 would be appreciated.

Thank you.

 

Where are you buying all the parts from?

 

Rock Auto

 

This is a well documented struggle over the last 15 years. Echlin Ignition, part # ECH DKS238 from Napa is what you want.

 

As @lucky131969 mentioned, the NAPA knock sensors have been one of the "known-good" replacement options around here. Lately it's been AC Delco knock sensors causing issues like yours, but perhaps in your case it's extended to NTK & Delphi, as well as GM (which may just be rebranded AC Delco).

There's a whole topic on the AC Delco sensors not working out for us where we started finding long-term success with NAPA ECH DKS238: https://www.corvetteforum.com/forums...ck-sensor.html

 

The ones that worked for me from Napa are https://www.napaonline.com/en/p/MPEDKS238SB
That is after I ran multiple NTK, GM and another set I can't remember. Not sure what the difference is from the ones mentioned above and the ones I bought that end with SB but they worked for me on a 99 that I rebuilt and then had issues until I bought Napa ones.

 

Good Grief!

Thank you for the replies. I will haul myself over to Napa shortly.

 

Just following others up saying the Napa sensor are what solved my issue as well as their harness.

Their rear tie rod end (toe arm?) is also a good part, but it does need to be greased once installed.

Double check while in the store that they are the right sensors though, a few people have mentioned getting Delphi and others in the box from people hot swapping them.

 

So I drove around 50+ miles on trips I know are long enough to throw codes. Miraculously the GM Genuine sensors have yet to throw a code, so I'm going to run them for a few days and I'll report back. Ignition timing still feels a little strange.