Есть еще такая инструкция:
At ambient temperatures around 70°F, the resistance of the heating element is approximately 4.5 ohms on 4.0L engines. It is approximately 13.5 ohms on the 4.7L engine.
https://zinref.ru/avtomobili/Jeep/06...NGLISH/379.htm
И, кстати, указано, что нижние датчики также участвуют в смесеобразовании:
DownstreamSensor(Non-CaliforniaEmis-sions): The downstream oxygen sensor (1/2) is also used to determine the correct air-fuel ratio. As the
oxygen content changes at the downstream sensor, the PCM calculates how much air-fuel ratio change is required. The PCM then looks at the upstream oxygen sensor voltage and changes fuel delivery until the upstream sensor voltage changes enough to correct the downstream sensor voltage (oxygen content).The downstream oxygen sensor also provides aninput to determine catalytic convertor efficiency.