Help with O2 voltage readings

[Klutch9]

A few weeks ago our Fusion sprung a P0130 code, accompanied by a CEL. I cleared the code using Forscan, but the code came back the next day. Oddly, it then cleared itself and hasn't come back, but fuel mileage has been [censored] ever since. I finally got around to using Forscan to take some live readings of both o2 sensors... once warmed up fully, the upstream o2 sensor stays stuck at 0.09 to 0.10v. If I shut the car off it shows 5.0V. If I restart the car, the readings start at about 1.0v and drop quickly to the 0.1v number. Doesn't matter what I do with the loud pedal, it's stuck. The data shows that the heater circuit is working. The downstream sensor hovers around 0.08v once warmed up, and with light throttle it stays there too; but a quick throttle blip will bring it down very close to 0.0 (lean), and then it goes back up to around 0.08. All seems well for the downstream.

Oddly, I'm not getting a CEL currently, but the code IS stored in the PCM when I scan the vehicle. Sounds like a bad upstream sensor, as the P0130 indicates?

 

[zrxkawboy]

Yes, I would say so.

 

[229]

I would use a Motor Craft for the replacement.

 

[Colt45ws]

Yup, replace it.
Isnt Forscan wonderful? I was able to diag a similar issue on my 2002 CVPI and see for certain that it was actually a bad O2 and not a code sending me down a rabbit hole. The heater wasnt working, though it wasnt throwing a heater code. The PCM was unhappy because the O2 was taking too long to warm up and that was what the code was for. I was able to compare its output with the other bank and verify before I spent the money/time on replacing it.

 

[clinebarger]

Don't go by the CEL/SES/MIL on Fords, Once P1000 (Diagnostic Checks Not Complete) sets.....You may not see a CEL until you fix the fault & get P1000 cleared via a complete drive cycle. The PCM is ABORTING the diagnostic checks & setting P0130 in the memory.

 

[Klutch9]

I do have a Motorcraft replacement in hand. It was actually one of the cheapest options on RA.

 

[Klutch9]

UPDATE: I just replaced the old upstream o2 with an OEM Motorcraft one... and it's still giving the ~0.1v reading once warmed up. And the downstream is still reading ~0.7-0.8V, which is extremely rich. I'm wondering if something is off with Forscan's monitoring, because I also had a real-time monitor up for measured AFR at the upstream o2, and it was pretty steady around 14.7-15.0:1 at idle, and would lean out real quick with a throttle blip, then return to normal. So it appears that it is working... I'm just so confused by these voltage readings! To make sure that Forscan wasn't somehow mixing up the readings, I unplugged the upstream sensor while the car was running, and all real-time readings for that sensor went blank, so I know it's reading the proper sensors. Any ideas? FWIW, I didn't think to check the AFR readings with the old sensor.

LTFT was at 1.56% also.

EDIT: This o2 sensor also gives a current output measurement, that goes slightly above and below 0. Do I have a wideband sensor perhaps? FOr example, on the new sensor, I got a real time reading of 14.991:1 AFR, with a 0.07mA reading on the upstream sensor. Again, I should have done this measurement with the old sensor, but I'm new to this

 

[clinebarger]

It appears that Automatic Transmission Fusions have a "Wide Band" & the Manual Trans versions have a "Narrow Band" upstream O2S, Both will have a narrow band downstream O2S.

Having the fuel trims read in such "high resolution" is also an indication you have a wide band, The WB sensor has 6 wires, A NB will have 4 wires.

Fords have had a HO2S milliamp PID long before wide bands were common.

 

[clinebarger]

Also, The P0130 is no longer setting in memory?? If not, Get the P1000 cleared/Monitors ready, If no DTC's set......Your good!!