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P0331 Knock Sensor

8.7K views 5 replies 2 participants last post by  Rob22315  
#1 ·
Van threw code for a bad knock sensor on bank 2. I'm going to get them both replaced. Based on a bit of parts research and a decent YouTube video (
), it looks like it's a major disassembly of the upper part of the engine, including removal of the oil filter adapter housing. One of the major sources of oil leaks on these engines is the gaskets in this housing. There's also coolant running through one of the parts that requires removal.

Accordingly, I'm also going to get the oil filter adapter gaskets replaced and the intake manifold upper gaskets as well. For future reference, here are the part numbers:

OEM Knock sensor (Rock Auto and eBay) - 39320-3C000

Fel-Pro Intake Manifold gasket set (found on Amazon) - MS 97086

OEM gaskets for the oil filter adapter (available from multiple online vendors) -
26343-3C100Engine Oil Filter Adapter Gasket$2.851$2.85
26347-3C100Engine Oil Filter Adapter Gasket$27.711$27.71
26345-3C100Engine Oil Filter Adapter Seal$2.751$2.75

Anyone have any tips or suggestions? It's too big of a job for me to do it myself but I have a shop nearby that will use my parts and does quality work for reasonable prices.
 
Discussion starter · #2 ·
One of the interesting things I noticed in checking this out is that the engine designers ran coolant over the oil filter adapter housing to help cool the oil in the engine. That looks like a nice design feature to make the engine last longer although creating a more complicated set of parts.
 
Discussion starter · #3 ·
I still don't have all the gaskets and seals and my mechanic can't do the work until next week but I need the van for a camping trip this weekend. I decided to do a bit of ******* engineering. :oops:

I was able to find where both sensors connect to the wiring harness. I'm guessing that bank 2 (per the error code) is the one at the back of the engine (farthest from the serpentine belt). I was able to unplug the existing sensor and plug a new sensor into the harness. I mounted the new sensor on a conveniently located hoist lift point with $2 worth of 5/16" hardware from Home Despot. (This idea came from the comment section of the video I posted above.) Total time for repair - 20 minutes not including the trip to HD for the hardware.

I've already cleared the error code from the computer so I'll test drive it tomorrow and see if it worked. I'll post results when I get something substantive.

The repair, done correctly, will cost about $150 for gaskets and sensors plus about $600 in labor at a cheap local shop.
 
Discussion starter · #5 ·
Its quite common for folks to assume an error code is an indication that the sensor has failed, whereas the error code should be used as the starting point in the diagnostics.

Out of all the sensors on the engine the knock sensors are very robust.

Hoping its not a real issue with the engine that was alerted by the error code.
Of course, but I tried measuring the resistance of all the sensors. None matched the generally accepted values of a couple thousand ohms. The new ones and the front sensor all measured as an open circuit. I think the assumption is that most of these piezo sensors have a parallel resistance built in for bias or fault detection but apparently these don’t. I wasn’t able to measure the rear sensor because the connector is buried under a bunch of stuff. Since I already have the new sensor, it’s easy enough to install it and see if it works.

Sure, diagnostics are almost always preferred but it’s not worth a couple hundred bucks or more for diagnostic tools I’m only going to use once or a handful of times. If I can’t fix it for cheap, I’ll take it to a place that hs those tools.
 
Discussion starter · #6 ·
Update: Sensor #2 (the one closest to the rotating parts on the engine) has definitely failed. I was able to connect a new sensor into the system, clear the code, and run the van for 100+ miles without a repeat of the error code.

I ended up attaching the new sensor to the hoist attachment point and it seems quite happy there. No more error codes and no knocking in the engine.

I may still get the complete replacement done at a later date now that I have all the gaskets. Or not . . .