Knock Sensor Diagnosis

Ally · Post by **Ally** » June 24th, 2007, 1:06 pm

Hi there, washed the engine and now the check engine light is on. Says it's the knock sensor. How can I diagnose exactly what the problem is? It has to be either the wiring, the sensor or the ECU right? Will I have to replace the gaskets if I take the intake manifold off? Also, is there any way other than disconnecting the battery to clear the engine codes? HELP! Oh its a 92 V6 MX3

Mnemonic · Post by **Mnemonic** » June 24th, 2007, 2:39 pm

something probably got wet, i'm guessing its fully dry now, try clearing hte codes (remove negative terminal from battery and hold down brake pedal for 30-60 secs) and then reconnect and see if it will pull a knock sensor code again.

if you remove the intake manifold you should replace teh gaskets, but just get you some rtv sealant and you'll probably be fine.

And in the future, no wash engine, thats a no no to much electrical, simple green, several clothes, carb and choke cleaner, and some latex gloves.

lot more work but better

Ally · Post by **Ally** » June 24th, 2007, 2:54 pm

Hello. Thanks for the tips. Tried to clear the codes, the light still comes on. I did a few tests with a digital voltmeter, and it looks like it's drawing power here and there, so the wiring appears to be fine. Any way I can test the ECU? What a headache!!!

hgallegos915 · Post by **hgallegos915** » June 24th, 2007, 3:23 pm

Its not the ecu, most likely the knock sensor, if you pull it out its probably still wet or its just corroded. My old k8, i replaced it it was 99 dllrs for a probe gt knock sensor. The old one was completely rusted.

Also once I did the mistake of washing the engine bay and got the code again. The connectors were wet. Disconnected cleaned them up and reconnect.

I reset the ecu and the code was wrong.

Ally · Post by **Ally** » June 24th, 2007, 3:29 pm

Thanks everyone for the info. Gonna try taking off the intake manifold, and screw around with the sensor. Any way to test the part when it's removed to see if it's dead?

Oh and before I even go there, do I special tool to do this?

Mnemonic · Post by **Mnemonic** » June 24th, 2007, 4:17 pm

not really set sockets a wretchet and some hexs, check out the online manual

Smith18 · Post by **Smith18** » June 24th, 2007, 4:51 pm

Mnemonic wrote:not really set sockets a wretchet and some hexs, check out the online manual

Well if hes taking out the sensor he will need a socket like a O2 sensor socket with a slot on the side of it, i think its a 24MM.

Mnemonic wrote:if you remove the intake manifold you should replace teh gaskets, but just get you some rtv sealant and you'll probably be fine.

NEVER RTV sealant on any intake stuff, its just not good cause it can dry and leave a ring around your runners and then over time its gonna fall off into the engine. Clean up around the old gasket before putting the new one on.

hgallegos915 · Post by **hgallegos915** » June 24th, 2007, 8:10 pm

I couldnt find the socket anywhere..so i bought the socket .. i think 24 , and with a grinder made the side hole for the electrical cable. The knowck sensor all it is is a microphone. Sometimes if your HLAS tap really loud, they will set off the knock sensor and the your car goes into lymp mode.

92BlAcKGS · Post by **92BlAcKGS** » June 30th, 2007, 7:05 pm

Hey, i have the same problem, i washed my engine and cleaned the intake out and now i got 05, Knock Sensor code coming up. Is it hard to change it or fix it. And if i don't change it will there be consequences, it only comes on when car gets to operating temperature, but car runs fine otherwise

Thanks

n2ogsze · Post by **n2ogsze** » July 1st, 2007, 2:57 am

You don't have to replace the IM gaskets if you remove it. They are not a crush gasket in the same way our headgaskets are. [/quote]

PATDIESEL · Post by **PATDIESEL** » July 1st, 2007, 10:49 pm

The intake gasket will usually fall apart when you take it off. I would recommend getting new ones. If your RTV leaks or you reuse the old one and it leaks you'll be taking it all back apart. That time is not worth it IMO and so I would just replace them with new ones.
As for the sensor, you can ohm test it to see if it is truely fried. The directions are in the online manual.
In the future be careful of elec stuff when washing the motor and don't crank it until the next day. Leaving the hood opened and doing it early on a sunny days helps the water dry out of any elec stuff.

92BlAcKGS · Post by **92BlAcKGS** » July 2nd, 2007, 4:50 pm

do u have an idea of the whereabouts of that information is on the online manual?

Thanks again

n2ogsze · Post by **n2ogsze** » July 2nd, 2007, 9:44 pm

PATDIESEL wrote:The intake gasket will usually fall apart when you take it off. I would recommend getting new ones.

Not sure where you are getting your intake manifold gaskets but each and every one I've dealt with on a K* engine has been made of steel. Steel=doesn't fall apart.