knock sensor info please.....

**vncj96** · 11-22-2016

i have never had an issue with a knock sensor on the 20 something cars i have owned with the hundreds of thousands of miles they have been driven. my 04 GPGT is giving me a code for the bank 2 knock sensor low circuit. changing it out is a PITA from what i have read in that you need to drain the coolant and go through the passenger wheel well to get to it. Please correct me of that is wrong or someone has a tip/trick to changing it out.

I would have thought that there would be an associated misfire for one of those cylinders on that bank as well. so i guess this makes me believe that its actually the sensor that went bad. Will the computer automatically try to add or pull fuel to get rid of a "knock"?? should i be worried about still driving the car with a bad knock sensor??

I have no issues about working on my own vehicles actually would prefer it, just have never had any experience with this particular sensor, more or less just looking for some education on the matter, thanks!

**SgtMarshal** · 11-22-2016

the knock sensors are located on the bottom part of the engine block. there is a single wire that goes to each. the one on the front is easy to see and get to, the one on the back is a pain because it sits in between the engine and transmission. you have to get under the car for access, but you might be able to see the front one by looking down, and is next to the spot where the oil dipstick tube goes into the block, you could look at that one as a reference to identify the rear one. it will be much easier to identify if you are under the vehicle.

the way the knock sensors work, is that they detect sounds of detonation inside the combustion chamber. when the knock sensor hears the detonation, the pcm cuts timing advance, which decreases pressure in the combustion chamber. fuel is not adjusted when knock is detected.

I'm not sure about the misfire part of your question or if something bad could happen if you keep driving it.

**J57ltr** · 11-22-2016

You will need to get it out from the passengers side behind the tire. Once you have it out then move it to the passenger side and push it up and over the trans case and fish it out with a magnet. I never got a code for low circuit, but I had weird horrendous off idle KR that would cause the engine to fall on it's face even with the knock sensors disconnected.

Low circuit is usually something like the sensor is shorted to ground or the wiring is chaffed and shorted to ground.

Jeff

**FordMan77** · 11-22-2016

Not sure how it is on the 04's but on the 97-03's the rear knock sensor wire is clipped to the PS resevoir or somewhere around there and gets damaged/ripped loose if the PS has been messed with. If you've had the PS pump removed for any reason may want to check it out.

**alenw62** · 11-22-2016

Yes I have pulled the wires out of both sensors connectors and if you have to buy new pig tails they are 24 dollars each do not damage them them

**chrisrexmandie** · 03-14-2022

Do the knock sensors go bad? I have my trans out currently and easy access to the rear sensor but dont believe mine to be bad.

**FordMan77** · 03-14-2022

They can, it's just a sensor. Personally if it was known to be working before then I'd just leave it. If you do feel like replacing it then I would get nothing but an OEM one. Something that is that hard to get to would not be fun if you have to do it again because of a cheap aftermarket part.

Thread: knock sensor info please.....

Thread Tools

Display

Similar Threads

Knock sensor

Po 327 knock sensor

Knock Sensor ???

knock sensor

knock sensor?

Bookmarks