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Category: Chevy
Satisfied Customers: 22533
Experience:  ASE MASTER TECHNICIAN ADVANCED LEVEL SPECIALIST. Wisconsin certified emissions state inspector
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92 chevy caprice: o2 sensor on the drivers side..tps..rotor

Resolved Question:

I have a 92 chevy caprice with a 305. I have replaced the o2 sensor on the drivers side, can't find another one. Also have replaced the TPS, thermosatat, plugs, wires cap and rotor. I keep getting the 02 sensor code of 43. That happens after I seem to lose power and the temp guage goes up. It does that for awhile and then the temp goes back down and it seems to run ok again.
Submitted: 6 years ago.
Category: Chevy
Expert:  AMEDEE replied 6 years ago.



Code 43- Knock signal is outside the normal voltage range. The normal voltage is 2.3 to 2.65 volts with no knock present.

Category: Chevy
Satisfied Customers: 22533
Experience: ASE MASTER TECHNICIAN ADVANCED LEVEL SPECIALIST. Wisconsin certified emissions state inspector
AMEDEE and other Chevy Specialists are ready to help you
Customer: replied 6 years ago.
I'm not a car guy so I do't now what that means
Expert:  AMEDEE replied 6 years ago.
This is a knock sensor code. DO you know what a knock sensor is?
Customer: replied 6 years ago.
No I don't
Expert:  AMEDEE replied 6 years ago.



The knock sensor is located on the LH rear side of Engine Block






The knock sensor is located in the engine block. The sensor sends a signal to the ECM, by way of the Electronic Spark Control (ESC) module, to retard ignition timing during a spark knock condition. When engine detonation stops and there is no knock signal being sent to the ECM, timing is advanced in small increments. This allows the ECM to maintain maximum timing advance under various engine load conditions.

Customer: replied 6 years ago.
What do I do to fix it and why does the temp guage go up?
Expert:  AMEDEE replied 6 years ago.



This will require some testing. The cooling system and the knock sensor and circuit will need to be inspected very close.


Electronic Spark Control (ESC) is accomplished with a module that sends a voltage signal to the ECM. As the sensor detects engine knock, the voltage from the ESC module to the ECM is reduced. This signals the ECM to retard the timing, if engine speed is over approximately 900 rpm.

TEST DESCRIPTION : The numbers below refer to circled numbers on the diagnostic chart.


If a Code 43 is not set, but a knock signal is indicated while running at 1500 rpm, listen for an internal engine noise. Under a no load condition, there should not be any detonation, and if a knock is noticed, an internal engine problem may exist.
Usually a knock signal can be generated by tapping on right exhaust manifold. This test can also be performed at idle. Test number one was run at 1500 rpm, to determine if a constant knock signal was present, which would affect engine performance.
This tests whether the knock signal is due to the knock sensor, a basic engine problem, or the ESC module.
If the module ground circuit is faulty, the ESC module will not function correctly. The test light should illuminate indicating the ground circuit is OK.
Contacting circuit 496, with a test light to 12 volts, should generate a knock signal to determine whether the knock sensor is faulty, or the ESC module can not recognize a knock signal.

* = ECM/IGN, #13, or # XXXXX fuse.
"Scan" tools have two positions to diagnose the ESC system. The Knock signal can be monitored to see if the knock sensor is detecting a knock condition, and if the ESC module is functioning. The knock signal should display "YES" whenever an engine detonation is present. The knock retard position on the "Scan" tool displays the amount of spark retard the ECM commands. The ECM can retard the timing up to 20 degrees





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