These are the diagnostic codes I'm getting after my 92 4runner check engine light started up last night. Are there really 2 unrelated things that happened to go at precisely the same instant, or does this indicate a third, bigger problem? The vehicle is running fine. I'm worried that my ECU is causing all of this, and I'm not bright enough to do electrical diagnoses
21= OXYGEN SENSOR SIGNAL/OXYGEN SENSOR HEATER SIGNALOPEN OR SHORT IN OXYGEN SENSOR OR OXYGEN SENSOR SIGNAL
43= STARTER SIGNAL--NO "STA" SIGNAL TO ECU UNTIL ENGINE SPEED EXCEEDS 800RPM--IGNITION SWITCH/CIRCUIT
--ECU