Got a '97 Plymouth Grand Voyager with intermittent O2 codes. Pulled two, "Heater Circuit Low Voltage", within about 2 months. Got a P0140, "O2 Circuit No Activity Detected", just the other day. CEL stayed on for about an hour of driving, hasn't come back on since. Turned itself off while driving. Fuel econ. seemed curiously poor while code light was on and for about a day after code turned off. May be that I was just paying closer attention to fuel gauge.. Both codes were for downstream sensor on cat.
Wiring/connector looks great on both the sensors.
Now, since the codes are coming and going, I would assume that the downstream sensor is starting to get tired. Not dead yet, but getting there. I have a nice OBDII scanner, I want to check the voltages. What range should they be reading at? I also think replacing them would be a good idea just as a, "tune up", repair, van has 127k with original O2's.
Anything else I should look at before replacing? I see that both sensors should be replaced at the same time, and I'd like to replace both, but the upstream could be a real to get a wrench on without a lift.. I can see it, but kind of out of arms reach, looks like the only way to get to it is from underneath, or by removing intake manifold. If it's worth just replacing the downstream sensor, as that's the one with the problem, I will just do that. Van's valve cover gaskets are weeping some, will need replacement in the future. I'd have to pull intake manifold and fuel rail to do that anyways, I'd tackle the upstream then...
Thoughts?
Wiring/connector looks great on both the sensors.
Now, since the codes are coming and going, I would assume that the downstream sensor is starting to get tired. Not dead yet, but getting there. I have a nice OBDII scanner, I want to check the voltages. What range should they be reading at? I also think replacing them would be a good idea just as a, "tune up", repair, van has 127k with original O2's.
Anything else I should look at before replacing? I see that both sensors should be replaced at the same time, and I'd like to replace both, but the upstream could be a real to get a wrench on without a lift.. I can see it, but kind of out of arms reach, looks like the only way to get to it is from underneath, or by removing intake manifold. If it's worth just replacing the downstream sensor, as that's the one with the problem, I will just do that. Van's valve cover gaskets are weeping some, will need replacement in the future. I'd have to pull intake manifold and fuel rail to do that anyways, I'd tackle the upstream then...
Thoughts?
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