Testing the knock sensor

Mad Cow · Post by **Mad Cow** » April 19th, 2009, 6:23 pm

I think I need a new knock sensor, and they're insanely expensive brand new, so I'm going to pull one from a junkyard. I read something about an ohm test to see if they're good, but now I can't find that post, and I can't find anything in the manual. So how do you test a knock sensor to see if it's good?

JWMX3 · Post by **JWMX3** » April 19th, 2009, 7:08 pm

all you can do is a resistance check. Set the meter to ohms and one lead on the +12 one on the gnd in the knock connector.
I bought one brand new from the dealer, if i remember right it was 125.00 or something....

I cant remember what the resistance spec is for the knock sensor, i'll try to find it and post back or im sure someone else will in the meantime

EDIT *** in the mitchell manual it dosent give a resistance spec, but with the ign ON, should have 2.4 volts on the knock sensor. it also says to use a digital meter. hope that helps !

Daveb · Post by **Daveb** » April 19th, 2009, 9:21 pm

I thought I read that the KLZE engine doesnt have a knock sensor, I m losing it.....

Something about putting a plate over the hole.....

I cant even find the knock sensor in my chilton book

Daninski · Post by **Daninski** » April 19th, 2009, 10:44 pm

You need to pull your intake and a coolant tube to access it. Why not post in the [WTB]. I'll have two by the end of the month. I'm sure others have spares as well. Cheers

fieromx3 · Post by **fieromx3** » April 20th, 2009, 3:38 am

its 120 bux brand new at mazda.... and pretty much all knock sensors are out of spec these days... there is a guy here that had a faulty one in his mx6 so he went to the wreckers and tested all of them and all of them came out bad as there out of spec... so he went to mazda and bought a brand new one and it was right in spec!

spend the 120 bux for a brand new one. do it right. have a shiny new mazda part

Daninski · Post by **Daninski** » April 20th, 2009, 7:47 am

Wonder if you even need it if you use high test gas?

fieromx3 · Post by **fieromx3** » April 20th, 2009, 9:34 am

without it ur ecu tends to go into limp mode.

Daninski · Post by **Daninski** » April 20th, 2009, 1:15 pm

Limp mode

Mad Cow · Post by **Mad Cow** » April 20th, 2009, 4:10 pm

fieromx3 wrote:its 120 bux brand new at mazda.... and pretty much all knock sensors are out of spec these days... there is a guy here that had a faulty one in his mx6 so he went to the wreckers and tested all of them and all of them came out bad as there out of spec... so he went to mazda and bought a brand new one and it was right in spec!

spend the 120 bux for a brand new one. do it right. have a shiny new mazda part

I remember reading something like that too, but I might as well try. So what's the resistance spec?

mx3autozam · Post by **mx3autozam** » April 21st, 2009, 7:45 pm

520milliohms...anything else and and the sensor is screwed.

Mad Cow · Post by **Mad Cow** » April 22nd, 2009, 8:06 am

mx3autozam wrote:520milliohms...anything else and and the sensor is screwed.

Do you know the margin of acceptable readings? (eg +- 30 milliohms or something)

mx3autozam · Post by **mx3autozam** » April 22nd, 2009, 10:39 pm

as far as I know if its not at that reading than its screwed. thats what someone told me

MX-3.com

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