I'm working on a 1990 NA automatic. I'm getting code 52 = Knock sensor and 25, 26. The owner said the knock sensor was just replaced a week ago.

I cleared the codes and I get code 52 within 1 min of driving. I checked for continuity between the knock sensor pigtail and the wire right before it goes to the computer under the dash.

Is this a common problem with the 1990 supras? Is there anyway to check if the sensor is bad or the wiring?

Thanks for the help

Tom

More than likely it's just not connected right, code 52 means knock sensor malfunction, I had it on my car after I had to worked on and they accidently unplugged it. Yes, it will throw that code and check engine light fast. Knock sensor is located under your intake, there are 2 on turbo models, and i believe one on N/A cars, I know there is one right above and to the front of the started, and the other one is farther foward than that. Look from under the car, they're pretty big, hard to miss.

Yeah, I think the NA only has one knock sensor. Can someone confirm this?

I wiggled it and took it off and reconnected it. The light came on within 1 minute of driving.

Could it have anything to do with aftermarket headers or a new head gasket? I think the engine was replaced with a Japan engine. I would not think that would have anything to do with the knock sensor?

The engine sounds perfect, but it runs rich which is probably due to the computer running in "limp" mode while recieving a bad signal from the knock sensor.

More input needed...

Tom

I have an 89 n/a. One sensor. Everything I've read on internet says its not a common failing part. Many have problems with wiring.
I doubt that code will make it run rich (unless you really are in open-loop while code is set).

Yeah, it's either a bad sensor, or bad wiring. If he changed it out, and did it wrong....

Is there any way to check the knock sensor?

On my Mazda MX6 the resistance across the knock sensor when the car is off is ~560ohms. Is there a check for supra knock sensors?

Thanks

Tom