Code P0328 faulty knock sensor circuit. Fixed.

Hello all,

After doing a ton of Google searching I decided to join up this forum and ask for help.

My wife's 2008 2WD Rav4 2AZ-FE has had a history of what seems like slight hesitation from a slow rolling start (maybe this is normal).

Just yesterday we got the CEL/traction/slip light combo. Took it to Autozone and pulled code P0328 which is for the Knock sensor circuit malfunction.

Last night before bed I went ahead and re-tightened the gas cap. This morning all lights were gone and it ran fine for my trip to Autozone for the code pull. Then the warning lights came back on and limp mode started while sitting in the Chic-fil-a drive thru.

Thought maybe I got some bad gas so I bought some STP fuel system cleaner (i know its crap) and filled up with 93 octane from a DIFFERENT gas station.

Brought it home and disconnected the battery for 30 minutes then started it back up, no lights, ran great for a 20 minute drive. Brought it home cut it off, waited 5 minutes then drove it around the neighborhood and it faulted out again.

So from what I've read, it is unlikely that the knock sensor itself is actually bad. Possibly a loose wire or connector? I'm going to start tearing the intake apart tomorrow to access the sensor for inspection/testing. I just wanted to know if anyone has had or heard experiences with this issue and could maybe offer some insight.

Thank you in advance.

A previous thread http://rav4world.com/forums/viewtopic.php?t=24055&highlight=p0328 has a poster discussing that a mouse chewed through the wire leading to the knock sensor. Looks like you have to remove your intake manifold to get the sensor. Is your 2008 out of warranty?

My sister has the same vehicle as the OP and she had a mouse chew through the knock sensor wire, too...(small world).

As the car was still under warranty, I didn't want to mess with it so she took it back to the dealer. Since it wasn't a defect in the vehicle, they wouldn't fix it under warranty, so she came home $800 poorer. Good news was that her insurance covered part of it so I think she was only out $300.

Stupid rodent.... :roll:

Dudenhymer said:

Looks like i'll be taking the intake manifold off soon and looking for mouse gnaw marks...

Click to expand...

While you are going in, you might want to take some pictures.

http://rav4world.com/forums/viewtopic.php?t=21687 is an example for a 3S-FE engine. Maybe you could start a thread for the 2AZ-FE.

I started a thread for locating parts on the 2GR-FE engine, but it does not have pictures of anything disassembled (other than removing the engine cover).

So I tore into the Rav today. After taking everything apart and getting the intake manifold off I found a bunch of mouse turds, feathers, chewed up foam and acorn shells piled up around the knock sensor. I also of course found the two knock sensor wires chewed all to hell... It's amazing, I'm the third person on this board to have the EXACT same problem with mice.

The intake manifold is bolted to the back of the engine. Between the manifold and the engine block is a fitted piece of foam that is supposed to insulate the manifold from the engine block. Well, this setup makes a nice cozy little spot for mice to make a nest. The insulation protects them from the heat of the engine. Inside this little mouse condo, the knock sensor is attached to the block. They were probably riding along wherever we went, sharpening their teeth on my KS wires!

It's really not too bad of a job. Didn't really need to take any pictures. I just listed on a piece of cardboard, every little step I took. Take connector off of this, take hose off of that, etc.

You basicall have to do this...

Remove engine cover 2- 10mm nuts.

Detach intake tube from throttle body. The top of the air filter housing has two electrical connectors and a handfull of hoses that need to be detached. After you detach everything you can pull the top of the filter housing and intake tube up and out of the engine bay.

The service manual says you have to drain the coolant so that you can detach the coolant hoses from the throttle body. You do not need to do this. after detaching the throttle position sensor plug and a couple of hoses, you can take the 4 bolts out of the TB and just pull it up out of the way. Tie it off to something to keep it out of the way.

CAUTION: There is a fuel line wrapped in rubber snaked in and around the throttle body and attached to the fuel rail. You don't want to stress this thing too much or you may kink it.

The manual also says you have to bleed pressure off of the fuel system so that you can remove the fuel rail. You don't need to do this either. Just unplug the electrical connectors to all 4 injectors fold them back out of the way.

After you disconnect a couple more hoses from the intake manifold you are ready to unbolt it. Manifold has 5 bolts and 2 nuts. Two of the bolts are more easily removed from underneath the Rav. The other 3 bolts and 2 nuts are easily accessable from the top.

You may need to peel the manofild from the head because the gasket will be sticking.

Now comes the tricky part. This is where taking the fuel rail off would have saved some trouble... You have to snake that manifold up and out from the top of the motor. Just take it slow, be patient and try not to break anything!

Once the manifold is off, crawl back under the Rav and look up toward the back of the engine. There is a cheezy (hence the mice) foam insert that is fitted to the back of the block. Pull that POS out of the way. I left mine out after fixing the issue so that another mouse couldn't fill the vacancy.

The knock sensor is pretty much the only thing on the back of the block. You can't miss it. There is a black wire and a white wire running to the connector that plugs into the sensor. My mouse had completely chewed both wires up. I believe they were shorting out intermittently.

I got some good electrical connectors from the hardware store. Just cut the chewed part out and replaced it with connectors. There are a million ways to do it, just make sure you do it right!

Now just follow the list of steps you wrote down and put everything back together.

Our Rav has 41K on the clock. I called the dealership to find out if they had an intake gaset and throttle body gasket. They had neither in stock. The guy on the phone said I could probably just re-use them, which I did. They are made of some pretty sturdy rubber. I just took them out and wiped them down, they were still in good shape.

I recommend using a torque wrench to bolt the maiifold and TB back down. The specs for both are 22 lbf. If you decide not to then be careful, the manifold is made of some sort of plastic and will probably crack if you get to strong with it.

Took me about 3 hours start to finish, which included running to the hardware store and also trying to get the Rav up on ramps without a running motor.

Guess I saved myself $800, time to hit the bar :cheers:

Good luck!

Dudenhymer, that was a good write up on the sensor wire repair. It is nice to know that you got by (so far) without the expense of an intake gasket set. For most such work a fresh gasket set would be recommended. I hope I don't have to deal with that issue but it appears we are vulnerable to mice damage there. So it was nice to see how you handled it.

http://www.rav4world.com/forums/viewtopic.php?t=23507&highlight=glue+trap suggests a glue trap in the engine compartment.