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O2 Sensor bad or not? 700

Don,

That doesn't sound like the typical varying O2 sensor signal to me. In fact "stable" sounds like a bad sensor. Could you tell us:

• What codes?
• How old is the sensor?
• Do you have Regina FI?
• If Regina, might someone have installed a Bosch O2 sensor?

Guessing it's Regina, and not knowing what codes, the green book says the voltage should vary between 0.1V and 1.2V (engine running).

If consistantly LOW, test the O2 sensor function (engine running) by unplugging the sensor lead and check voltage with grounded meter. "After a while" the voltage should rise to 1.2v.

If voltage rise fails, check heater voltage, etc....

Also, from your later post:
". . .the signal from the O2 sensor seems very determined...let's see, if it goes to 0.12V that means that it's trying to enrich the fuel ratio."
• The sensor has no direct mixture control, it's just indicating a lean mixture. If anything, the ECU is trying to lean out a rich mixture.

"Also, the voltage is correct for cold at .54V."
• Sorry, but I have to ask where you found a "correct" cold O2 sensor voltage spec — although it seems about right for open loop ECU operation.

--
Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.






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