Today I interrogated the ECU on my very pedestrian 96 Civic LX sedan to diagnose a "check engine" light and got ECU code 41: Failed Pri O2 Sensor Heater. So, 3 questions for the wizards:

1. Anyone else ever have this fail? Is it real failure or just a disconnect?
2. Where exactly can I find this widget on the engine?
3. If it is a heater failure, where can I get one online?

Thanks for the expertise, folks....

 

The primary O2 sensor is located near the engine and somewhere on the exhaust manifold/down pipe. There is a secondary O2 sensor after the catalytic converter mounted on the exhaust pipe.

Your ECU is indicating the heater on the primary O2 sensor has failed. The ECU saw an open heater circuit. This could be caused by open wiring, poor connection, or of course a failed heater.

The heater is part of the O2 sensor and cannot be replaced by itself. The heater's job is to get the O2 sensor up to operating temp more quickly on a cold engine. Earlier cars have only a single wire O2 sensor and rely soley on exhaust heat to warm them up. If the CEL doesn't bother you too much, there's no harm in driving your car for a while until you find a replacement sensor.