ECM code 43 = Knock sensor?

[ProEMTPFF]

I have a '86 with just under 6k miles now, not a typo 6k miles.....really. I received a "service engine soon" light today and checked for a code. The code I have is #43 and the possible failure is "Check ECM wiring. Replace knock sensor". First is where to go to check the ECM wiring and second is what is a knock sensor, where is it located, what does it do? Thanks in advance for your help.

 

[Ken]

The ECM is located up under the passenger side hush panel, but it's rare that you'd have a problem with that wiring. You may want to check the wiring between the knock sensor, which is located on the right side (passenger side) of the engine block, and the ESC (the Electronic Spark Control, located in the right fender area near the windshield washer bottle and heater blower) for any indications of excess wear.

Most likely it's the knock sensor that's throwing the code.

 

[ProEMTPFF]

Thank you for the reply. Since I posted this here I have been told that 99.99% of the time a knock sensor needs replacing is breaking it while changing the starter. Should I check the wiring as suggested and reset the code before just jumping in and changing the sensor?

 

[Ken]

Check the wiring.

 

[rrubel]

Unplug and re-plug the wires to the ESC (where Ken mentioned it). Had a similar code with my Vette and that took care of it - must have been some crud on the contacts.

I did replace my knock sensor, but it WAS NOT throwing a code. It was disconnected, and the pigtail had been tie-wrapped to the frame on purpose by a previous owner. The sensor is on the bottom of the block, just in front of the starter by the exhaust manifold. It's a pain to get to, and you get covered with coolant when you remove it. Do you get knocking under acceleration?
[RICHR]

 

[ProEMTPFF]

I have yet to hear a single knock.

 

[rrubel]

I was getting really back knock (as you'd expect with the sensor disconnected) but not once did I get a knock-sensor-related code. Just the ESC one. I *think* they're two separate codes on our year, but my book is in the Vette, which is at the shop.
[RICHR]

 

[onedef92]

Also, check the knock sensor wiring for oil, grease, grime, etc... Sometimes this can cause the sensor to throw a code on your DIC, especially if you get the SES alert moments after start-up.

If you remove it, I believe the correct torque is 15 lbs. Do not OVER or UNDER tigthen as this can cause false readings, too. The plastic acoustic coupler (a little nipple looking thingy) IS very sensitive and easy to break off. They run about $40 each, but I think you L-98 just has one whereas the LT-1 has 2 sensors.

If you can't get it off using a breaker bar/ box-ended wrench combo or a socket wrench, you can use a pair of vice grips to get a good bite on the round part of the sensor. It's hardened metal and won't loose its grip like the little nut on the end tends to.