Hello;
I am new to this site as a member, but, have checked it out a lot over the years for advice. So, if I am not in the correct place to pose a question, please let me know. I work on my truck myself when I can; 2005 Ranger Edge, 3.0; (mainly oil changes, tune-ups, radiator flushes..general maintenance)...It is my second Ranger. I bought one (Ranger XLT, 4 cylinder) in 1996 (new) and it had over 300 K miles on it when my son wrecked it and I am certain it would have still been on the road if he hadn't. I bought my 2005 new and I have had more issues with it than I have ever had with my '96. So far, I have replaced the fuel pump twice; had to replace a valve, clutch, and now the O2 Sensors. I just replaced the downstream O2 sensor yesterday, but, before I replace the upstream sensor, I wanted to be sure that I have located the right sensor. The parts store told me that I have 2 O2 sensors, so, I hope they are right. Question; can anyone tell me where the upstream sensor is located? Right (passenger) side? or left (drivers) side?

Thanks!

 

Hi,

This section is OK for questions but more people will look at it in the discussion forums.

'96 and up 3.0l Ranger will have 3 O2 sensors, in 1996 Ford switched to the EEC-V computers with OBD II, these have the ability to monitor Catalytic Converter operation using an O2 sensor

There will be 2 "upstream" O2 sensors on a V6(or V8) one for each Bank(side) of the V engine.
There will be one on each down pipe from exhaust manifold before they connect to the "Y" or go thru a Cat Converter.
These 2 sensors help computer control Lean/Rich air/fuel mix.

The 3rd O2 sensor will be on the "downstream" end, after the Cat Converters, this sensor is used by the computer to see if Cat Converters are cleaning the exhaust.
Computer compares upstream readings with downstream readings, this O2 sensor can not effect engine operation, it is just for emissions.
This sensor rarely fails since it is in a cleaner exhaust stream.

All 3 sensors are the same part number, so can be interchanged.

The names of the sensors are:
Bank 1 sensor 1 (passenger side upstream)
Bank 2 sensor 1 (drivers side upstream)
Bank 1 sensor 2 (downstream)

Bank 2 sensor 2 (if a vehicle has dual exhaust all the way back, then it will have 4 O2 sensors, 2 downstream instead of one)

Upstream O2 sensors can "wear out" but if engine hasn't had any "running rich" issues to foul them they can last a long while, I replaced my '94 Ranger upstream O2s last year at 300,000 because my MPG had gone down a bit, turned out one of them had started to to unscrew itself(bank 1), so air was being sucked in and making that bank show lean, so I was running rich and MPG went down.
Since I had already bought them I did the swap, but old ones were probably still working fine.
MPG is back to normal now in any case.

 

Thanks so much for responding! I called O'Reilly's and asked them how many sensors my truck had and they told me 3 (the place I bought the sensors from told me I had 2 ) so I need to purchase one more sensor. Unfortunately, the Bank 2 sensor (on the drivers side) is a real bugger to get to so I will have to jack up the truck to replace it. I had to soak the downstream sensor with PB Blaster for 24 hours before it would budge so I am assuming that I will have to do the same with the others. My truck had codes that indicated it was running rich and my CEL came on. So, I changed out the wires and plugs, cleaned the MAF sensor and now I figure I should change out the O2 sensors too. But, after changing the downstream sensor, I wasn't real certain where the "second" sensor was since there was also one on the drivers side. I guessed that there more than 2 at that point. So far, my CEL is off and my truck seems to be running smoother and I am hoping that the gas mileage improves as it went from an average of 320 miles to a tank to about 270. It should be a lot better once the other 2 are replaced. Thanks for your help!