Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
I have E53 x5 BMW 2004, the car stay on open loop, both O2 sensor show 0v. But there is no engine light on. The owner said, it consume a lot of fuel. I was suspecting it's the O2 sensor fault. Does the downstream O2 should operate as it should or should it also shows 0v too? by the way, the ECT shows normal temperature around 98C.
Check power and ground of heater circuit of 02's. Could be a blown fuse. Are you seeing 0v in scan tool pid? KOEO unplug 02 does voltage stay at 0v or show voltage? If 0v signal wire shorted. If voltage sensor is bad.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does
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