Code P0140 ? help
#1
Saturn Ion 2004..19041 miles..My check engine light came on and I stopped at Advanced and had one of the guys read the codes.He said it was code P0140..he went on to say the code reader said no voltage going to (or through) the O2 sensor.He said to check to see if the wire had fallen off the sensor.Getting ready to check that but knowing what those plugs look like I doubt it simply fell off.Any ideas ? This car used to belong to my mother and was never driven above 40 until last year when I got it and I drove it to Florida which I was planning to do in about 5 days until this light popped on.Could it be any thing to do with the 19000 miles being a time to get something checked?Thanks in advance.
#2
Well, I would touch base with your local dealership, and see if they have any information as to previous service(s) performed on that vehicle. Once I had that in my hands, it would point to any service(s) that was needed immediately.
Loss of power to the downstream O2 sensor might cause the vehicle to have low MPG, and you will not be able to pass a SMOG test if you need to renew your certificate.
Loss of power to the downstream O2 sensor might cause the vehicle to have low MPG, and you will not be able to pass a SMOG test if you need to renew your certificate.
#3
No previous service other than oil changes.
Is there any test I can do on the o2 sensor? I checked the fuse for the sensors and its good.Can I test the wires going TO the sensor?
Edited by: 12v testlight
#4
You have to find the reason for the loss of signal from the O2 sensor. It could be a bad connector or an open sensor.
Voltage is being output to the sensor, otherwise there would be a P137 or P138 (voltage low/high). P139 would indicate a signal being returned, but no change detected from the sensor.
P140 says no signal is being returned from the sensor (open circuit).
Voltage is being output to the sensor, otherwise there would be a P137 or P138 (voltage low/high). P139 would indicate a signal being returned, but no change detected from the sensor.
P140 says no signal is being returned from the sensor (open circuit).
#5
Originally Posted by OceanArcher
You have to find the reason for the loss of signal from the O2 sensor. It could be a bad connector or an open sensor.
Originally Posted by OceanArcher
Voltage is being output to the sensor, otherwise there would be a P137 or P138 (voltage low/high). P139 would indicate a signal being returned, but no change detected from the sensor.
Originally Posted by OceanArcher
P140 says no signal is being returned from the sensor (open circuit).
Thanks for reading my long post and Happy New Year.
edit-One last question-Should or can I do a comparison test with my ohm meter using the forward 02 sensor to compare readings ?
Edited by: 12v testlight
#6
I really do not know if you can compare cold readings with the upstream unit or not (never tried it). I have tried, however, to use an after-market (generic) part - it did not work for me, but I would defer comment to others here on the Forum with more experience in this area. Low Saturn or SW2cam or Derf just to name a few ...
#7
Originally Posted by OceanArcher
I really do not know if you can compare cold readings with the upstream unit or not (never tried it). I have tried, however, to use an after-market (generic) part - it did not work for me, but I would defer comment to others here on the Forum with more experience in this area. Low Saturn or SW2cam or Derf just to name a few ...
#8
That sensor is the final check of the exhaust. Basically monitoring the health/well-being of the catalytic system.
You are right in the assumption that a steady-state lamp indicates a fault, and a flashing light indicates a failure of a more serious nature.
I would continue my trip, and have it serviced when I arrived at my destination (but that is my opinion - feel free to do as you see fit).
You are right in the assumption that a steady-state lamp indicates a fault, and a flashing light indicates a failure of a more serious nature.
I would continue my trip, and have it serviced when I arrived at my destination (but that is my opinion - feel free to do as you see fit).
#9
Originally Posted by OceanArcher
That sensor is the final check of the exhaust. Basically monitoring the health/well-being of the catalytic system.
You are right in the assumption that a steady-state lamp indicates a fault, and a flashing light indicates a failure of a more serious nature.
I would continue my trip, and have it serviced when I arrived at my destination (but that is my opinion - feel free to do as you see fit).
You are right in the assumption that a steady-state lamp indicates a fault, and a flashing light indicates a failure of a more serious nature.
I would continue my trip, and have it serviced when I arrived at my destination (but that is my opinion - feel free to do as you see fit).
If all I did was clear the computer memory how long (if in fact the sensor is an open circuit) will it be before the computer recognizes the "open" and turns the check engine light back on?
If the open has actually disappeared should I assume the open was a result of a connector and not the sensor because I couldnt have done anything to have repaired the open inside the sensor by simply moving wires? (the sensor doesnt receive any grounding from its thread connection in the exhaust does it? )
Thanks
#10
If it was simply a loose connection, you should be good to go.
If the sensor is truly inoperative, it may take a little while before the PCM detects the inactivity, and sets the code again. I do not know what the time delay is necessary for that to occur ...
If the sensor is truly inoperative, it may take a little while before the PCM detects the inactivity, and sets the code again. I do not know what the time delay is necessary for that to occur ...