jonah

Also: what might be causing it to fail?

Prospeeder

Well, im certain you would have codes. BUT i have seen several times that shorted o2 sensor heater elements or shorted o2 heater wiring causes ecu failure. For some seriously flawed reason the heater wires go directly to the ecu.... The ecu is located in the plenum chamber? The seal in the connector is gone, too much moisture getting in. Not bolted in or secured correctly so its bouncing around causing damage. or just poor quality replacments.