I had posted before about changing my O2 sensor on a 97 Subaru Legacy wagon with an OEM sensor and the check engine light came back. I received great responses (Thanks : ) One of them was to multi meter the wire coming from the engine side of the bank one sensor two oxygen sensor which sits right on the catalytic converter. I multi metered the wire using a positive and the negative with the ignition on engine off. There where three wires, two positive and one negative. I got a 10 ohm reading from one positive and no pulse from the other. Could this be the problem?
O2 sensor light is on. I multimetered the wire from engine side.Found what I think is the problem. Need advice
It sounds like the cats.
O2 sensor light is on. I multimetered the wire from engine side.Found what I think is the problem. Need advice
You have few (possible) problem. You'll only get a reading when (a) the engine is running (b) O2 sensor is warmed up.
The only last problem is that digital multimeter (DMM) are often TOO SLOW to respond for you read the value. Some non-auto-ranging meters are little bit faster but by not much.
Some DMM have %26quot;bar graph%26quot; on top that can move as fast the pulse (even if the digital readout is still hunting). There are few LED bar-graph O2 (or exhaust gas oxygen - EGO) meter you can hook up. They are little more than 0-1 volt meter. But they react very quickly.
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Another thing is that you want to be reading the VOLTage not the resistance (ohm). When the engine is running at stoichiometry (14.7 : 1 - perfect air to fuel ratio) the voltage should be near 0.45. But in practice it should bounce little bit above and below that (about 3 to 10 times per second). But that's only during idle or cruise. At wide open throttle (WOT) the engine ignores the O2 sensor and just dumps fuel (at something like 12:1 A/F ration).
