The other day I came off the interstate, hit the ramp onto Rt. 10, popped the pedal down to accelerate out into traffic and the check engine light came on. No change in the way the car ran/felt. Drove it on home. Checked the code - code 43. Low voltage to the EST system. Pulled the code reader out, hit the key, no light. Ran it down the road to get some pizza for supper and it ran like always.

Never saw a code 43 the whole time I've owned the car.

Is this code sometimes intermittent? If so any idea what might cause it, or should I just wait to see if it comes on again and dig out the big old shop manual and work through it?

Thanks.

 

code 43 is for your knock sensor. Check to make sure the plastic connector is seated correctly on the knock sensor. It is between no. 6 & 8 cyl (blue wire), but before you do all of that i would just disconnect neg. battery cable for a few to clear the code and see if it comes back.

 

IIRC, this code is created only when at WOT. I get the same code sometimes when I get on it, but the code always goes away. For now, I'm just waiting for the intermittent code to go full time so I can find out what is broken.

 

code 43 is knock sensor.

 

Code 43 Diagnostics per the manual: System performs a test once per startup to check the ESC system. To perform this test, ECM will advance the spark when coolant is above 90C and throttle is at WOT. The ECM then checks for the signal at B7 to see if a knock is detected. If no knock is detected the SES light will remain on until the ignition is turned off or until a knock signal is detected.

 

Sensor between cylinders 6 & 8 in the head is for Heavy Duty Coolant Fan High Temperature switch (if you have dual fans,) connector is same type as Knock Sensor which is in the block just above the oil pan rail in front of starter directly above cross member. The knock sensor wire color on my '88 is white, and temp switch wire color is gray.
I'm not sure single fan cars have the high temp fan switch.

 

Yeah the fan switch (only one on my single fan IROC) is right there near the plugs. The knock sensor is down nearer the oil pan. I smack the gas pedal on a regular basis on that car. Always have. Just never had that code before. The only one I ever got on a semi regular basis was the EGR (code 32 if I remember correctly) but even that's been a couple of years or more since it lit the check engine light.

Drove it again today. No issues. Man, that thing is still fun to drive, even after all these years.

Thanks for the info.

 

yeah,it's been a while since i have looked,but yes you are correct the knock sensor is further down below 6&8 cylinders. On my 91' the knock sensor wire is blue.