'94 Ranger 4.0 auto trans. How many are there and where is it/they located. Thanks

 

4 O2 sensors total. 1 upstream/before the cat converter/1 downstream after the cat converter, in each cyl bank exhaust line. The up stream sensor tells the computer how much O2 is in the exhaust flow, so it knows how well it's doing controlling fuel trim/fuel injector squirt time, in each cyl bank.
The after cat sensors tell the computer how well the cat converter is doing cleaning up left over exhaust putrids.
Be sure to replace the O2 sensors with the specified like kind.

 

Yep. Don't cheap out on your O2 sensors. Stay away from the budget replacements from RockAuto or your local auto parts store.
And it's my opinion that the rear two sensors RARELY need to be changed.

 

On a '94? This is an OBD1 system, I'll have to check but I'm pretty sure our '94 3.0 only has 2 at most.

 

Conanski, You're saying that there are 2, 1 upstream and 1 downstream or 2 upstream? Please check.

 

My truck only has 2 upstream in the head pipes just below the manifolds.

 

Thanks Conanski. I just read another forum and he said

90-92 there is 1 before for the catalytic converter.

93-94 there are 2 off each manifold. Like about 10-12" down the y-pipe.

95-up' There are 2 like mentioned before and 1 after the catalytic converter.

I just ordered 2 for my '94.

 

This might vary by the model and the engine. SOME Ford models actually had a beta OBDII system in place before '96. ('96 was when OBDII was mandatory at most all cars) If my memory hasn't completely failed, the '94 and '95 3.8/V6 Mustang cars had a very primitive OBDII system, yet the '95 Mustang with the 302 had an OBDI system.
I'd definitely crawl under the vehicle to inspect before ordering O2 parts for any car/truck of this era.

 

There were regional differences too, California gets everything a year or rwo before the rest of us.

 

I did look for them and there were only 2 after the exhaust manifolds. It looks like the passenger side is going to be tough to change.

 

OK, that's good feedback, so now the confusing info I'd found is beginning to make some sense....maybe lol.
The Ford Parts web site here http://www.fordparts.com/Commerce/Ca...=Ranger#Search, shows 2ea of O2 sensor P/N's
9F742(DY-713) & 9F742(DY-733) BUT the wiring schematic here BBB Industries- Premium Alternators, Starters, Power Steering Products (Look/sign in under Tech Info for wiring & TSB info), only shows Two O2 sensors for the 94 4.0L???!!!

No Motorcraft site parts folks to contact until Mon. Looks like the dim's are a little different on the two parts, so if the vehicle only has Two sensors, it looks like maybe it take One ea of the two parts???

My 94 Taurus 3.8L has Two O2 sensors in each down pipe Before the cat converter & One O2 sensor After the cat & none of my manuals show anything about it having O2 sensors!!!??? Go figure!!!!

As has been said, Lots of emissions changes were being made in the late 94-96 time frame & from what I've read over the years there seems to be a dukes mixture of emissions equipped vehicles out there from that time frame, so it's safer to search using the vehicle VIN #.

SO Alex, back up to the Motorcraft Search page & enter your VIN # into the Motorcraft web site search page, Before you order any parts, to see if anything different may show up.
West coast emissions equipped vehicles (Cal) especially, in that time frame, seemed to be the worst for all kinds of emissions configuration changes being made early on. My 94 Taurus had Cal emissions, probably why it's so confusing for me when trying to look up reliable info about it!!??

More thoughts for consideration, let us know what you find.

 

Thanks PawPaw. After looking and reading the label, it's not a CA truck, there are only 2 sensors. I ordered two Bosch 15718 sensors yesterday.

 

Ok, the Bosch site here https://www.boschautoparts.com/en/auto, says this 15718 is the exact fit for your 94 non Cal emissions 4.0L.
I'd compare the Motorcraft site published length, as they show Two different lead lengths, so to see how they match up.
If the leads are long, you can dress them up with cable ties, but we can't stretch too short a lead, so you might need two lead lengths/different PN, so check Both sensors lead lengths out.

I used the specified Bosch models on my 94 Taurus before cat O2 sensors about 7 years ago & they fit just fine, wire length & electrical connectors were right, plugged right in like OEM & the threads already had high temp anti-sieze compound already applied, although it seemed a little wimpy, so I carefully added a little more Permatex nickel high temp anti-sieze, being careful Not to get any on the sensor end.
Don't use any silicone grease in the electrical connector, as the Bosch O2 sensors are designed to Breathe air through the wire connections, so it can get an accurate external O2 Base Reference measurement against which to measure an accurate O2 level in the exhaust flow. So adding grease as some folks say to do, will corrupt the sensor base reading & thus corrupt fuel trim by sending the computer an inaccurate reading. Just follow their installation instructions. The ones in the Taurus are doing just fine for 7 years now.
One of the OEM sensors began setting an intermittent CEL with a slow/lazy switching trouble code, so it was time to change out both of those upstream O2 sensor puppies.
I opted to use the Advance Auto "Loan-A-Tool" O2 sensor removal socket set & was glad I did, as the cyl bank one sensor was in a Really tight spot that required the shorty/offset socket to get that puppy out. Both came out ok though, as the factory had used anti-size & we don't have badly salted roads in winter, so not much rust binding things up for me.

More thoughts for consideration, let us know how it goes.