If there is a transformer or a ferrite cored inductor on the circuit board that lies in the presence of a static magnetic field then that can alter their electrical characteristics.
We ALL lie in the presence of a static magnetic field. The Earth has a significant one. Driving your car in circles does not affect performance.
Further, all current carrying wires are surrounded by a magnetic field. If there is an alternating current in the wire that is in the presence of a static magnetic field, Then the wire will be alternately attracted toward and repelled by the magnet. This can set up a physical vibration that can induce secondary unintended electrical currents in the wire as a side effect.
The wire will also be attracted to the steel in the car. Being that you've created an electromagnet with ZERO windings, the magnetic forces exerted on the wire will be similar to the electrostatic forces it experiences due to the capacitive coupling with the vehicle frame, i.e. negligible. Each time the driver breathes, the vibration will move the wire more.
However, O2 sensors have a very slow-changing voltage -- essentially DC, with very little current...
I suppose you have never seen the output of an O2 sensor on an oscilloscope. They are most certainly not DC.
If there is a transformer or a ferrite cored inductor on the circuit board that lies in the presence of a static magnetic field then that can alter their electrical characteristics.
Further, all current carrying wires are surrounded by a magnetic field. If there is an alternating current in the wire that is in the presence of a static magnetic field, Then the wire will be alternately attracted toward and repelled by the magnet. This can set up a physical vibration that can induce secondary unintended electrical currents in the wire as a side effect.
However, O2 sensors have a very slow-changing voltage -- essentially DC, with very little current. So long as the wires are not moving from vibration in the magnetic field then no noise currents will be induced.
My comments inline in blue:
My comments were within the context of an extremely strong magnetic field as asked by the OP, and are simplified to apply directly to the question. Modern "rare earth" magnets commonly have magnetic fields on the order of 30MGOe; your comparisons with earth's magnetic field is laughable. With over 30 years experience as an electronics design engineer I stand by my comments.My comments inline in blue:
I'm saying that it is possible to affect the signal within the limited circumstances I described, but very unlikely to affect it enough to cause a problem.Rare earth magnets are much stronger than your ordinary ones, as I'm sure you know, and this one was right up against the 02 wires which I'm sure vibrate while the vehicle is running. The reason I'm asking is I just want to eliminate that as a possible cause to a P code.
Correct me if I'm wrong but it sounds to me as if you're saying that it is possible for the magnet to alter the signal.
I am wondering if you bought into some crackScience gadget that save you fuels ?
^^^
(Reason saying that is there are usually no magnets or ferrite rings anywhere along the O2 wiring.)
I think a strong enough magnet will distort the signal... but a magnet in the wiring will never increase gas economy or performance but might increase imaginary horse power.
I'm saying that it is possible to affect the signal within the limited circumstances I described, but very unlikely to affect it enough to cause a problem.