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Discussion Starter #1
Hey...i pulled a knock sensor code from the ECU. What does that mean?

Does it mean that it had retarded timing? componet bad?

Can i just disconnect it or could that lead to serious engine damage.

BTW I am using a JWT ECU.
 

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Cause and repair instructions (long)

It means that the knock sensor is opened or shorted. This means an abnormally high or low voltage has entered the sensor. You should check the harness and connector, and the sensor itself.

Start by checking the input signal circuit. 1)turn ignition switch off. 2) Disconnect ECU harness connector and knock sensor harness connector. 3) Check harness continuity between terminal b (the right terminal) and ECU terminal 27. Continuity should exsist. If does not exist check the following: Harness connectors F1, E201; harness continuity between ECU and knock sensor. If not good then repair the harness or the connectors.

If continuity did exsist then you need to check the sensor itself. Disconnect the knock sensor harness connector. Now check the continuity between terminal a (the left one) and the ground. Continuity should exsist. If no good, replace the knock sensor. And when you replace it, do not drop it, or it will break. If it checks out good then check out the ECU pin terminals for damge or the connection of the ECU harness connector.

After the repairs have been done you need to run a final check. Run the diagnostic test, take a test drive, then perform diagnostic test again. If there are no problems, you are done. If there are, recheck the ECU pin terminals for damage or the connection of the ECU harness connector. Repair the damage and do the final check over again.

These instructions were taken directly from the FSM. So you will need the FSM electrical wiring maps to locate where these connectors and terminals are. If I had a scanner I would post them up for general reference, but alas I don't. I hope this helps some.
 

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Discussion Starter #3
Hey thanks...what kind of multi-meter should I buy?

And i have the FSM here...but im not sure how you check the connectivity between the harness and the b on the knock sensor?

Also, how far back is my timing retarded becuase of the ECU putting the knock sensor in fail safe.
 

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Multimeters

A380Driver said:
Hey thanks...what kind of multi-meter should I buy?

And i have the FSM here...but im not sure how you check the connectivity between the harness and the b on the knock sensor?
If you want a meter to last your lifetime buy a Fluke brand meter. Even if you RUN over the meter, Fluke will replace it at the standard repar cost. They stand behind their products FOREVER. Best of all, it is NOT made in China. For basic use, you need one for AC and DC volts (house and car) and ohms (continuity). For more advance uses, you will want one with current also (amps). For advanced automotive use, they have a specialized automotive multimeter that has dwell and rpm functions. For the basic meter a Fluke 10 will work, about $75. Advanced, Fluke 23, about $200. And Automotive Fluke 88, about $350.

Continuity is checked by setting the meter to Ohms and connecting the meter leads between the wires to be tested. It should read less than 2 ohms (for very long wires) to less than .5 ohms (shorter wires). About .1 to .2 ohms will be your meter lead reading (connected to each other).
 

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Discussion Starter #5
Update on the knock sensor...fixed.

Knock Sensor Malfunction
When the output signal of the knock sensor is
abnormal, the ECM judges it to be malfunctioning.
When knock sensor is malfunctioning, ignition
timing will retard according to operating
conditions.

Eek...I didnt think it did that, but you learn something
new everyday. So I rembered that back when I was
at the dealer a while ago, we put the consult on and
it pulled a knock sensor code (which is one of the codes
that does not trip a check engine light) and he cleared
it and told me not to worry about it.

Well...I have a JWT ECU so i really didnt feel like having
a stupid sensor retard my timing...so I called Jim and
he told me that their ECU will still perform that timing retarding
function, which is about 5 degrees back. Ouch.

Hmm...went down to the car and sure enough pulled a
code 34 which was the knock sensor. Went to the FSM
to see where that puppy was and wow...is it buried WAY
up there attached to the side of the engine. It is basically
right about underneath the intake manifold in the center of
the block. For this you need to jack the car up (jackstands
or garage with lift) and reach WAY up in the middle right
past the center support and exhaust.

Note: DEFINITELY let the car cool down alot before doing this.

The bolt is a 12mm and I tried every combination of socket/swivel
heads that you could think of, but there was too much crap around
it. So I finally took a 12mm wrench and managed to manuever my
hand up there enough to get just enough leverage to move that
tight bolt.

Note: There is only one wire running to the sensor...so dont
freak out like I did

Per the FSM, I used a multimeter to check the connectivity in Ohms
between the "A" connector on the knock sensor and a ground.
None...so I had a bad knock sensor.

So onto searching for a new part. Becuase this is a somewhat critical
part on the car I didnt want it giving false readings and potentially
sensing false knock. An aftermarket one probably would be ok, but
I didnt want to take the chance. I found one from Bosch for like $102,
but I opted for the Nissan one at $155. I guess if im spending that
much I might as well get the real deal. Especially cuz I didnt want to
have to go through the trouble of replacing one of those again.

Note: They usually dont stock these, so be prepared to wait a day...
or order one in advance if you think you need it.

So just something that you guys might all wanna check...becuase it
*does* affect your timing if it goes bad, but no check engine light,
only a code.
 

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A380Driver said:
Per the FSM, I used a multimeter to check the connectivity in Ohms
between the "A" connector on the knock sensor and a ground.
None...so I had a bad knock sensor.
How do you disconnect the knock sensor? I have seen a lot of posts that seem to indicate there is a metal clip on the bolt that retains the sensor. I didn't see that, but I did see a metal ring around the connector. Does anybody have pictures that show how to separate this ring(If that's the right ring to take off)?

Any good ideas to gain leverage on a wrench that's on the knock sensor bolt? I got it on there, but couldn't move it for the life of me. Is it safe to put penetrant on the sensor?

How in the world did you manage to test the sensor while it was on the car? Did you just pin your arm up in the car with one lead and put the other lead to whatever ground you could find in front of your face?
 

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well the knock sensor plugs is a metal clip that when you pull on it hard enough it will pop off. The other option is to take the sensor out with the cable attach and then go ahead and pull the metal U ring out and disconnect it that way if you're afraid of breaking something. I ran into a problem taking the 12mm bolt off... I ended up having to take the whole intake manifold, plenum, throttle body and colant lines off so I could take mine out. It took me 2 days to take one stupid bolt out....
 

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So the metal clip is a U? It kinda felt like it. If I pull hard enough under one side of it, will it pop off? Any recommendations for a tool to do it with?
 

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well you can just pull and wiggle and it will come off.... it's kinda like the clip that goes to the temp sensor... if you really have to get the metal thing off, use a flat screw driver and pry up the sides a bit without twisting them too bad, the thing should pop off. But Id suggest wiggling and pulling first...
 

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i am ordering one for my car off of ebay. i am waiting to see if my buddy can confirm if it is the correct p/n, since my car doesnt have the stock motor in it. It is $62 shipped, versus $130 from the dealer. it hesitates bad, since the timing is retarded quite a bit. funny thing is that i cannot hear pining or knocking at any speeds.
 

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Here's the easy way:

1. Unbolt sensor.
2. Pull cable up through the manifold from just behind the fuel rail.
3. Undo little metal clip in full view, rather than blind while it's still on the car.
4. Bolt it back on, if you want to test it on the car.

OMG, that took me a few hours...
 

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dphilp said:
Here's the easy way:

1. Unbolt sensor.
2. Pull cable up through the manifold from just behind the fuel rail.
3. Undo little metal clip in full view, rather than blind while it's still on the car.
4. Bolt it back on, if you want to test it on the car.

OMG, that took me a few hours...
Yea a lot of people stumble at number 1 :-\
 

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Another point of confusion:

Which terminal is the left terminal? On the car, it looks like the left terminal would be the one on the left if the beveled side were facing up. On my new sensor, there is only continuity between the metal base and the right pin, if the beveled side is face up. I checked this against the old sensor, and the readings were exactly the same.
 

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It mentions to use a meter that can measure more than 10M ohms. I just checked my spare and it's around 15M ohms on the left terminal and direct continuity on the right terminal.

In a later FSM it says... Resistance: 500 - 620k ohms [at 20°C (68°F)]

I'm going to warm mine up a little and re-test it.
 

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markbuts3 said:
I'm going to warm mine up a little and re-test it.
Perv :shhh:
 

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markbuts3 said:
It mentions to use a meter that can measure more than 10M ohms. I just checked my spare and it's around 15M ohms on the left terminal and direct continuity on the right terminal.

In a later FSM it says... Resistance: 500 - 620k ohms [at 20°C (68°F)]

I'm going to warm mine up a little and re-test it.
557k ohms of resistance between ground and left terminal at around 20*C
 

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Hi,

I have a P10 G20, and I'm trying to determine the meaning of a code I am getting from the ECU, Code 34, Knock Sensor.
I tested the resistance on my knock sensor the other day, and I got .3 Ohms when I set the multireader at the lowest setting (200 Ohms). I don't know if this is good or bad.
I only tested the resistance on the knock sensor itself, not the wire harness.
I could not find the prescribed resistance for the knock sensor when I was looking in the manual. Do you know what it should be? or below what number?

Also, does the engine have to be warm when testing the knock sensor?

Thank You
 

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I see Mark's post above that says 557k Ohms is the expected resistance.
What is confusing to me is that each time I touched the terminal on the KS (which was still installed when I measured resistance) my multimeter read .3 Ohms.
How/ Why would I get a reading of .3 Ohms consistently? I'll be testing the harness next.
 
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