SES Light Came On - P0327

[RoGuE]

Our 2002 Suburban with the 5.3L triggered a code intermittently today, P0327 Knock Sensor 1 circuit low input. From what I have read, it is either a loose or frayed wire leading to the knock sensor, or the sensor itself is bad.

How do I go about diagnosing it? And until I fix it, is it safe to drive the car or could it damage the engine?

 

[01rangerxl]

Ouch, looks like the intake manifold comes off to replace them...


There's more than one YouTube video for this repair on this engine.

 

[dailydriver]

Yes, the intake manifold MUST come off to change these (make sure you replace the eight individual intake manifold gaskets with NEW ones, and it probably would not be a bad idea to replace the valley cover gasket as well while you're in there), or to get to the wires/connectors (as well as to; change the oil pressure sender, cam position sensor, and MAP sensor as well).

I still do not know what the 'default' ECM mode is with a bad knock sensor (or sensors), but if you use premium, and keep from going WOT too often, you should be OK (what I did when mine went out).

 

[RoGuE]

I watched a couple other videos that show how to do it and I now see it involves removing the fuel rail. That might be a little out of my comfort zone...I've done things like spark plugs and swapped out a water pump, but nothing like nearly as intensive like tearing into the engine. I'm sure I COULD do it, but out of curiosity, how much do you think a shop would charge to do this?

 

[vssjim]

It's a fairly easy job and yes I would replace both sensors while in there and the gaskets for the intake.

 

[RoGuE]

Should it be okay for another day or two? This is my dads car and he has a 15 mile commute each way to work. It's about 1/4 tank down in gas, would it be wise to fill it with premium until I can get to it? I'm afraid of it blowing on him from detonation.

 

[01rangerxl]

If it's really pinging bad all the time, I would not drive it, but if you can drive it so there is not much pinging and use premium, it will probably be okay. A little pinging won't kill it.

 

[RoGuE]

It doesn't seem to ping at all.

 

[01rangerxl]

You can drive it then, you will definitely hear detonation before it does damage.

 

[Merkava_4]

Originally Posted By: RoGuE
I'm sure I COULD do it, but out of curiosity, how much do you think a shop would charge to do this?


Big money. For the money you'd save from doing the job yourself, you could easily buy
an Alldata subscription for the instructions and all the tools you need from Snap-on.

 

[dailydriver]

Originally Posted By: Merkava_4
Originally Posted By: RoGuE
I'm sure I COULD do it, but out of curiosity, how much do you think a shop would charge to do this?


Big money. For the money you'd save from doing the job yourself, you could easily buy
an Alldata subscription for the instructions and all the tools you need from Snap-on.


Yes, and although I was reluctant, and NOT looking forward to doing it (it took me the better part of a full day, but I also thoroughly cleaned out the intake manifold/TB/etc., ports, and valley area), I did it!

The fuel rail (nor the injectors) should NOT have to come off, you just need to disconnect the fuel rail's fitting from the fuel line with one of those quick disconnect tools sold in ALL of the auto stores.
Of couse, you should take off the gas cap, and relieve the pressure from the fuel rail's schrader valve, and use a vacuum cap to cover the fuel rail fitting's end before lifting it off of the heads to keep raw fuel from spilling EVERYWHERE.

 

[RoGuE]

I know you mentioned earlier to change out the oil pressure sender, cam position sensor, and MAP sensor while I was in there, but is that really necessary? Are they a high failure rate part like the knock sensors? The engine has about 135k on it.

As far as all the parts go, I'm looking to get them at Advance due to getting a discount when buying online. They have an ACDelco knock sensor, and a Delphi ($1 more). I assume the Delphi is the OE part so it should be good?

Also, I see two Felpro gaskets on there. One that connects the gaskets with metal, and for $20 less one that uses plastic...

 

[mechtech2]

You may not hear spark knock.

Using one grade higher octane may be the cheapest and best option for short term safety..
At least for a while.

If those sensors are tripping the computer prematurely to retard the timing, you have to replace them.

 

[RoGuE]

How critical is using a torque wrench for this job? I have been able to get by without using it for a transmission pan and a water pump by just snugging up the bolts...

 

[RoGuE]

Out of curiosity, I made a couple call to two local dealers. Both say it is three hours of labor. Total cost is over $700.

 

[dailydriver]

Originally Posted By: RoGuE
Out of curiosity, I made a couple call to two local dealers. Both say it is three hours of labor. Total cost is over $700.

Yes, that is about what I was quoted as well, both by dealers, AND indies.
I did not say that one has to change out the O.P. sender, and CMP sensor while in there, just that the WHOLE intake has to come off again in order to do those (along with new intake gaskets EACH and every time

), so if one can swing the Rock Auto prices, it's not a bad idea.

My CMP sensor made it to 135K miles (AFTER I already did all this for the knock sensors), the O.P. sender, and MAP sensor were still functional, but I DID NOT feel like doing this all over again, for the THIRD TIME, anytime soon, so I changed it ALL out the last time.

A torque wrench is advisable for the intake manifold bolts, since the composite material of the manifold is VERY easy to crack with too much torque (unless you are VERY careful/restrained with pressure applied).

I tend to go with Delphi (the ones who made the actual original stuff on the pre-'04s??), mostly, before being split off from GM/Delco, who's current stuff could possibly come from China

), if it's available.

 

[RoGuE]

You've definitely convinced me to go ahead replace whatever I can. Here is an order list in my cart at Rockauto. I have a couple duplicates that I just need to decide on which one. Like the MAP sensor I'm deciding between the ACDelco part and the Delphi, and the gaskets, where one is held together with plastic and the other is steel. Also, I can't quite find the oil pressure sender on the part sites...is it the same thing as a switch?

 

[dailydriver]

Originally Posted By: RoGuE
You've definitely convinced me to go ahead replace whatever I can. Here is an order list in my cart at Rockauto. I have a couple duplicates that I just need to decide on which one. Like the MAP sensor I'm deciding between the ACDelco part and the Delphi, and the gaskets, where one is held together with plastic and the other is steel. Also, I can't quite find the oil pressure sender on the part sites...is it the same thing as a switch?

Yes, I'm sorry, it IS called a "switch" on there (and i believe by GM at the dealer as well).
I just used the Fel Pros the first time, and then the Delcos the second.

I did not realize ANY of those were steel backed, are you sure you are not looking at the valley cover gasket (which IS steel backed)??

 

[RoGuE]

If you type part #: MS 98016 T into the Advance Auto Parts website, you can see the steel backed gaskets there. Think they're worth the premium?

In general, are the MAP, OP Switch, and CPS hard to replace? I found a guide for the OP switch elsewhere... that doesn't seem hard and saw someone was even able to do it with the manifold still on, though I could see how it's a lot easier without it.

Also, in the meantime, I went up one grade of gas to 89. Hopefully it will be okay for a little while longer like that.

Also, I have some black high temp RTV from couple years back. How would that work to seal up the knock sensor covers to make sure moisture doesn't get in?

Edit: I forgot to ask, does anyone know what the procedure is to check if the fault is in the wiring or the knock sensor itself when using a multimeter? My Haynes book doesn't even mention a procedure.

 

[mechtech2]

I'd install the KS to the proper torque. It may be internally damaged by being too tight, and may not function right if too loose.