Knock Sensor

[Ant]

My 2005 4Runner with 137,000+ miles has just been diagnosed with a bad (faulty etc) knock sensor.

The CEL, VSC OFF lights are on and that is the code it showed.

Last time this happened it was my gas cap. Apparently no such luck this time.

(it's also in the shop for an exhaust noise)

My mechanic said it will take a long time (aka expensive) to get to the sensors and troubleshoot them. It's many hours of labor.

I was hoping to keep the truck a little longer before moving on to a newer 4runner. (I am not happy with the redesigned look of the front end from 2014)

Any thoughts on the sensor? Can I drive the truck and just ignore it and the lights (apparently he was not able to reset the CEL lights) or does a bad knock sensor cause the truck to run differently?

I don't know the actual code # just what he told me.

Thanks

 

[Phils4th]

Max power and efficiency comes from when combustion pressures are at their maximum and the piston is slightly (5-10*) after top dead center. Since fuel burns at a fairly even rate, we must advance the ignition timing of the spark plug as rpm increases so that the pressure is at its maximum 5-10* after tdc. The knock sensor tells the computer to retard ignition timing because it has sensed detonation. Which is when the spark plug lights off the mixture, but increasing temperature and pressure in the combustion chamber light off a separate area in the chamber, and these two flames collide and cause a knock sound and can cause serious engine damage. The computer is dependent upon the knock sensor because it will retard ignition timing when it senses detonation. Otherwise, the computer uses a fixed ignition advance table. This is why premium fuel delivers more power. Premium fuel is more resistant to detonation, and the computer can give the engine more spark advance without the knock sensor constantly retarding timing and taking away power with it.

If you must drive the vehicle, be gentle on it, do not floor it and avoid high rpm. Run premium fuel only and do not tow anything til it is fixed.

 

[RonJR]

You won't damage the engine by driving with a knock sensor code, but the truck will likely run poorly, with less than normal power and poor fuel mileage. A knock sensor (KS) code means the ECU (engine computer) isn't getting a signal from the KS, so it retards the timing to ensure no damage to the engine. That results in poor performance as described above.

You'll also be missing traction control and vehicle stability control (VSC). Not too much of a factor on dry roads, but possibly of concern in wet or slick conditions.

If you have emission (smog) laws in your area, you likely won't be able to sell the vehicle privately until you get the problem fixed. A dealer will probably accept it "as is" as a trade in, at a reduced value.

I would not plan to ignore the problem long term. Often times it's just the wiring, but still requires work to get to the connections and troubleshoot just where the issue it.

 

[Ant]

Thanks guys.

The truck has been rock solid and served me well. It sucks that something like this costs so much to repair. Some little sensor they buried inside the engine.

I guess I have no choice but to repair it, something I expected. But it will not happen until next week. So I will drive it over the weekend and just take it easy.

 

[Wet Willy]

Thanks guys.

The truck has been rock solid and served me well. It sucks that something like this costs so much to repair. Some little sensor they buried inside the engine.

I guess I have no choice but to repair it, something I expected. But it will not happen until next week. So I will drive it over the weekend and just take it easy.

How much did you pay to get it fixed? Shop wrote me an estimate for 2400 because of 16 hours of labor. Kind of hard for me to spend that type of money for a little sensor.

 

[Mpcuse1]

Knock sensor

How much did you pay to get it fixed? Shop wrote me an estimate for 2400 because of 16 hours of labor. Kind of hard for me to spend that type of money for a little sensor.

I just had the same issue, mice got in and chewed off the wiring. My shop charged me $800 in labor.
Knock sensors, wiring harness and gaskets less than $100, very inexpensive for parts. Too daunting a task for me to attempt.

 

[Wet Willy]

I just had the same issue, mice got in and chewed off the wiring. My shop charged me $800 in labor.
Knock sensors, wiring harness and gaskets less than $100, very inexpensive for parts. Too daunting a task for me to attempt.

Wow! How did you find out mice chewed it out. I dont have the money to fix it so I am just driving it.

 

[762NATO]

New to the forums as I'm chasing down a few issues as my baby gets older...
It's actually not that bad of a repair.
I smoke tested my 04 V8 this morning to chase down a vacuum leak and found that my lower intake gaskets were cracked and leaking. Upper was fine, so I took off the entire manifold to confirm and ordered the parts. I was going to service the injectors and install the gaskets when they arrive tomorrow.
I thought about replacing the solenoid plunger, starter contacts, and knock sensor but didn't order the parts because I figured if I could disassemble it in 3 beers it couldn't be that expensive of a repair, guess I was wrong. Guess I'll order them tonight.

Where do you recommend buying your genuine Toyota parts from and is there anything else I should replace while I have the upper and lower manifolds off?

Thank you!

 

[HIMILESV8SPORT]

I worked at a dealer when my KS failed. Several master techs didn't want to tackle the job and I did it myself. I replaced both sensors and the starter while I had the intake off. New sensors, intake gaskets, plugs and starter were around $600. Sensors were OEM and gaskets, Denso plugs and starter from RA. I'd gladly paid up to $300 labor as it took me about 6 hours and starter bolts were a major PIA! no longer at a Toyota dealer, I've been using Toyota Online Parts | Genuine Toyota Parts | Toyota Parts Online for any high dollar parts.

 

[Steve Theodore]

Hey guys,

My own 2008 4Runner Sport V6 has also thrown engine code P0333 and it was caused by rodents chewing on the wiring. The book time to replace/repair is a whopping 16 hours (Toyota) but I have a good mechanic who says he can do it in 4-5 by minimizing disassembly.

The rodents got me good this year unfortunately, as they chewed a few wires, but the knock sensor is the most difficult and time consuming section of wiring to replace.

I have a thread devoted to this issue here in case anyone wants to follow along: Multiple error codes caused by rodents: P0020, P0333, P0348