PSA: Rodent proof your engine before it's too late! (P0333 - DIY Knock sensor harness repair)

Aww rats!!!

P0333 Error Code:
One lesser known, but VERY expensive issue to have repaired on modern Toyotas is the knock sensor wiring. The root of the problem is that many Japanese manufactures have switched their wiring looms over to a soy-based material instead of petroleum-based (this switch occurred on Tacoma for the 2012 model year and 4Runner on the 2011). This means critters find them yummy! Critters will gnaw on the knock sensor wires until they short out on each other, causing an error code. The reason critters always go for the knock sensor wires is quite simple. They are tucked in a warm, safe, and secluded part of the engine bay. Perfect bedtime snack for a mouse making a nest.

Symptoms of a shorted knock sensor wire are severe: The truck will be in LIMP MODE!
-Will not shift into 5th gear/overdrive
-Runs with spark timing severely retarded (awful MPGs and no power)
-no cruise control
-no traction control


To have a dealer repair this is often a multi-thousand dollar job. Some people claim they have gotten their insurance to cover rodent damage if they had comprehensive coverage… after a deductible of course.


To avoid this issue? Spray rodent repellent under the intake manifold now! It only takes 1 mouse 1 night to cause these problems.

Parts / Retail Cost:
$40 - Replacement knock sensor wire harness (82219-08010) - I didn’t end up needing this, but get one incase you do
$42 - replacement manifold gaskets
$25 - Rodent repellent spray

Resources:
https://www.tacomaworld.com/threads/knock-sensor-replacement.235717/
https://www.tacomaworld.com/threads/rodents-chewing-knock-sensor-wires.517687/
https://www.tacomaworld.com/threads/knock-sensor-questions.456772/
https://www.howtopreventratsfromeatingcarwires.com/2017/02/10/does-your-car-have-soy-based-wiring/


Time:
The factory service manual quotes 20 hours for this job, but also calls for removing the cylinder heads… my slow self did it in 6 hours and only had to take off the intake manifold. It helps if you have someone with small hands nearby!


Tools:
-T40 Torx bit
-8mm allen
-10mm socket
-12mm socket
-wiring tools


Procedure:

This will be your first clue of a problem… P0333 - Knock sensor not reporting, bank 2 (drivers side) in addition to the TRAC OFF light. Check engine light reappears immediately after clearing the code. The TPMS light is on for a different reason.




As a backup, got some replacement manifold gaskets, a replacement knock sensor harness, and some rodent repellent spray.

Turns out after I got everything apart I got the wrong gasket set… luckily mine were in great shape.




Start by taking the engine cover off, 2 10mm nuts.

Then remove the air filter housing, a few 12mm or 10mm nuts, the throttle body clamp, and a vacuum hose in the back.




Remove the black intake plenum by disconnecting all the myriad of things attached to it including the throttle body… You will need an 8mm allen key socket for the bolts going into the intake manifold.




The fuel rail will need to be unbolted, as it will need to be moved around to get the lower intake manifold off.




When removing the T40 torx bits for the intake manifold, ignore the security bit torx head bolts. You don't need to remove those. Only the normal Torx head bolts.




With the manifolds off, we now have access to our working area… probably a good idea to cover the intake ducts.



The culprit will be found underneath these hard coolant lines, you will just have to reach around them. Small fingers help…




The chewed knock sensor plug wire!




Notice the straw? Evidence of a mouse nest!



You should be able to disconnect the plug and maneuver it around the coolant hardlines. Here was how much mine was damaged. These wires shorting on each other was the source of the error code.




Mine were chewed almost all the way through so I went ahead and cut out the chewed parts, extended, and soldered the wires. If yours are chewed too close to the plug to be repaired, that is when the replacement harness section is needed.




Last step before putting it all back together. Spray the heck out of the area with this stuff.




Success! Ignore the TMPS light…

The truck runs great again! The whole limp mode thing basically made it undrivable.

 

Same thing happened on our Honda Pilot.

 

Damn good thread, OP. Thanks for taking the time to put it together.

 

Nice write up. I found a mouse nest with a ton of bird food in my air intake box against the filter.

 

thanks, weren't any good how to guides when I was googling it last week so I decided to make one.

 

Great job on the thread. I can now worry about things I knew nothing about 5 min. ago....

 

Does anyone know of a good way to block access to that space? I know at least one person who had the problem filled in the space with hardware cloth while fixing/replacing the wiring so rodents couldn't get back in for a repeat. Wondering if there is a way to restrict access without taking the engine apart?

I protected the air intake with hardware cloth as I had found minor signs of occupation at the air filter.

 

FWIW - solved the problem on a Jeep Commander with a couple of mouse traps and Decon....... My Tacoma lives in a garage with a cat.....

 

When I had my Sonata I found dog food under my engine cover, and teeth marks on my air filter box. I learned my lesson that an automatic feeder in the garage is a bad idea.

 

Yeah, I use to keep bags of chicken and bird feed in the garage. Bad idea, just attracts the mice. I keep everything in sealed metal feed containers now.

 

FYI, a few dryer sheets in the engine bay can help too

 

I got back home from a 10 day trip yesterday to my check engine and trac off lights on. I was reading your build thread while on the trip so I knew the second I saw those lights that the knock sensor wires were done for. Sure enough, drove the truck and it felt supper sluggish and wouldn't shift into 5th. Dropped it off at Toyota this morning. They quoted me $2700!! Luckily my comprehensive insurance IS covering it, so I'm pretty happy considering the situation.

I'll for sure be rodent proofing the engine bay when I get the truck back next week. Thanks for the write up @Ripcord. Although I'm not repairing it myself, it was really helpful to reference. I was able to diagnose the problem immediately.

 

How bout this : I know someone who would feed the deer Sweet Feed and kept it in his barn/ garage until the bears smelled it and ripped the door off of said barn/ garage . My friend who own the house that Mr Sweet Feed lives in told him do not feed the deer anymore problem solved . So he proceeds to lock up the sweet feed in his car trunk parked in driveway well guess what ,trunk lid ripped right off of car along with the tail lights and wiring

 

Always had concerns of this happening when parked out camping etc, is there anything of the sort i can place in the engine bay that will deter rodents / squirrels etc from crawling up inside of the engine bay that i could place when i got to my location then remove when i drive away?

 

Nope,doesnt work.

I had the problem of mice getting into my cabin filter and on my engine. Put dryer sheets and moth balls to keep them away.

Found another nest in my cabin filter and one of the dryer sheets from the engine bay was part of the nest.

 

I had this exact problem too, but it was chipmunks and he died in the engine galley, I guess didn't get out before the heat got to him... It was VERY expensive but my insurance did cover some, worth talking to your insurance CO. if this happens to you...

This write up should be made a sticky...

 

I put mouse repellent bags and dryer sheets in my outboard motor then shrink wrapped the engine and the little fuckers got in and built a nest right around the repellent. I should have taken pictures and sent them to the repellent company!

 

I’m going to check my cabin filter right now

 

Hope it doesnt look mine did.

Pro tip- Put a piece of cardboard under where the cabin filter is as you pull out the filter.That way whatever is on top of the filter wont fall into your blower fan.

Ask me how i know what its like to pick out dead mice babies from the fan

 

Filter good , cleaned it with compressed air ,next time it will be replaced ! Good tip !