O2 Sensor Faulty - '90 240
The check engine light is on. Ran the diagnostic and got 2 faulty codes. 2-1-2 Faulty O2 sensor or wiring and 3-3-4 TPS in idle.
2-1-2 O2 sensor. How do I know if it is faulty wiring or faulty sensor itself? I know I can replace the sensor fairly easy (with the right tools and muscle) but the part is $$$ and I don't want to waste my money if the wiring is the actual issue. 3-3-4 TPS in idle. Does this have something todo the the O2 sensor?? From what I've read its another wiring issue or incorrect adjustment. How would I go about the next set of diagnostics and testing to make sure I'm not wasting my money? Id really appreciate some advice thank you!
2-1-2 O2 sensor. How do I know if it is faulty wiring or faulty sensor itself? I know I can replace the sensor fairly easy (with the right tools and muscle) but the part is $$$ and I don't want to waste my money if the wiring is the actual issue. 3-3-4 TPS in idle. Does this have something todo the the O2 sensor?? From what I've read its another wiring issue or incorrect adjustment. How would I go about the next set of diagnostics and testing to make sure I'm not wasting my money? Id really appreciate some advice thank you!
You can test the O2 sensor with a volt/ohm meter. The fat green wire is the output - the 2 black wires go to the heater. 12v +and - are on the black wires, there should be very little resistance through the two black wires on the o2 sensor (there's just a resistance heater in the sensor) the fat green wire - you can measure voltage - connected and running the voltage should flash between ~.3-~.8 volts. You can artificially change the o2 output voltage easily to see if will respond to a rich or lean mixture. Disconnect the green wire and hook a voltmeter to the black o2 lead of the sensor (and ground) . With the engine running ground the green wire from the body to someplace close on the firewall - this will tell the ECU that it's lean and will richen the mixture - you should see the voltage increase to maybe 1 volt. Then lick a finger on each hand, hold the green wire between your fingers in one hand in one and touch the positive battery terminal with the other - this will send a small voltage (through your body) to the ECU telling it that it's rich and lean the mixture out. You should see the voltage decrease - maybe to 0.
And smart move to not just replace parts that you have not proven are bad. You can drive the car without the O2 - it's function is to make sure the Mixture is exact for the converter to operate most efficiently.
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