Code 43 (EST Detonation Control)

Check connection between detonation sensor and harness. If connection good, disconnect wire at sensor and turn ignition on. Check voltage between sensor harness connector and ground.
If reading is less than 4 volts or over 6 volts, check circuit A23 for shorting to ground or shorting to voltage.
If reading in step 1) is 4-6 volts, check resistance across detonation sensor terminal to ground. Reading should be 2550-3450 ohms. If reading is bad, replace detonation sensor. If reading is good, check for weak connections at terminals.