HO2S 1 HEATER CIRCUIT
PCM provides about 0.45 volt reference to HO2S 1. HO2S 1
sensor signal voltage varies from about one volt when exhaust is rich
to about 0.1 volt when exhaust is lean. When ignition is turned on,
battery voltage is supplied to HO2S 1 heater to provide for faster
sensor warm-up, thus allowing sensor to become active in a shorter
period of time. PCM reads amount of time necessary for sensor to
become active after start-up.
You will likely notice poor fuel economy and possibly a SES light.
- O2 Heater element resistance is high
- Internal short or open in the heater element
- O2 heater circuit wiring high resistance
- open or short to ground in the wiring harness