: DTC P0332 Knock Sensor replacement TSB #02-06-04-023A

08-11-09, 11:13 PM

After a few family weekend trips and about 300 miles covered since the rebuilt of my truck, I got a few DTC codes that needed attention, mainly cyl 8 misfires, and knock sensor bank 2 low input. I didn't find much info on this site about the replacement of those, nor about the TSB above. Only 2002 escalades are covered. Maybe the design got better for 2003 up? Anyways I plead guilty in washing the engine compartment a few times, I like it when its clean! This didn't help the rust issue around the sensor...

Removed on this pic the intake tube, 2 clamps and a braket that holds onto the coolant hose. The 3 plastic covers are held by 8mm nuts, one in the center for the middle one, sides have 2 each. Note the nicely cleaned TBI (without removing it) that I did after reading here about rough idle.


Removing the harness on the injector requires a bit of practice! I did the first few that are easily accesible with a small screwdriver to get the hang of it, then I was able to take em off by hand. You need to pull out the clip then pull up on the grey plastic lock, then push on the tab and pull on the connector to remove it from the injector. I unplugged the coils on the picture, but that wasn't necessary as they are not on the same harness as the injectors.


I separated the fuel injection pipes in 3 components, this way I didn't have to mess with the special tool needed to remove the flexible hose (which I more often than not get leaks afterwards). T20 to remove crossover pipe on both sides, T25 for the bracket where to flex pipes are. Gently prying up removes the injector rails.



In order to remove the TBI, you need to drain a bit of coolant. I had the engine block heater to install, and was already planning to replace the Dexcool, so I drained the system via the lower rad hose. Here is a pic of my notsocleanfrombehind TBI!


Removal of the intake was very straightforward. 8mm all around starting from the outside loosening em gradually from the center. I was being overly carefull not to snap one off! All went well. The job would have been easier by removing the EGR valve system, but the bolts on the exhaust manifold were not collaborating. I feared one would break off so I tried to move the pipe while lifting the intake out of the way, it works.


Intake off! I was very surprised to find the intake tracts on the heads so dirty! I've seen diesel engines with twice the miles cleaner than that. Injectors were also covered in carbon deposits. We will get to that later.

Knock sensor bank 1 (front):


Knock sensor bank 2 (rear):


Removing the harness from the knock sensors wasnt easy! No real usefull instructions from the GM manual, and its hard to see in there, but I managed to get them out with 2 small curved hooks tools on easy side to pry out the tabs to remove the connector on top.



After removing the 2 sensors, there was 1/2 inch of water in the rear cavity! I cleaned the area as best as I could with a dremel. I also cleaned the intake inside and out, TBI, and all injectors with engine degreaser. I did not replace the harness, it looked in perfect shape. I replaced both sensors with aftermarket ones ($38 each). Heres is the finished result:


After washing the intake as best I could, I forgot to put back the front foam piece underneath. GM recommends removing the rear one. Also its hard to get all the water out the intake! I let mine blow dry overnite cause I could still hear water inside when shaking it!


I cycled the key on-off 5 times prior to starting the engine to fill up the fuel system, truck started just like nothing happened and idled perfectly! No coolant or fuel leaks. I will be tcheking the torque on the intake bolts after a few 100 miles to be safe.

The whole process including the removal of the 2 drain plugs for the coolant (u can read about in another thread) took about 3 days of work on and off. The P0332 was still in ECM memory when I replugged the battery but MIL wasn't on. Idle and performance sure improved from the engine. No more misfires, but the code P0332 came back (after a week or so) after I erased it with my Innova scanner. I will put a few more miles on the truck before I investigate further into it. Hope this helps someone.

09-21-09, 09:28 PM
Update: I wasn't able to get rid of the darn P0332 code that easily. It kept coming back after deleting it everytime we would drive on the highway. I tried adding a resistor to make the two sensors match exactly in measured value, no luck. Swapping the two signals made the code change to the front sensor, so I knew then the rear sensor I installed was bad, or I didnt clean the cavity properly upon reinstalling. As a fix, I wired the two inputs on the front sensor. Works great and I finally got a green light on my Innova scanner (I/M readiness ok) after 3 months! It's my understanding that this code sets when there is a problem with the sensor, not because there's a noticeable knock. If that would be the case timing would be altered by the PCM to compensate for the knock. Something to consider for those who might get this trouble code and don't feel like removing the intake and spending over $100 for the sensors. My advise would be to use OEM sensors. Good news is one less light on in the dashboard! :thumbsup:

04-28-14, 08:08 PM
where did you get the wire diagrams for the knock sensors

the cadillac man
04-28-14, 09:20 PM
where did you get the wire diagrams for the knock sensors

I can help with that