Question about 2002 Ford Escape
Sensor 2 is upstream or downstream
Hi I'm having same problem and I would really appreciate if I can get the diagram of where exactly each sensor goes. Thanks I have v6 with side engine and would like to know where to install all 4 sensors . Thanks
Posted on May 27, 2016
I\'m not a certified mechanic. I learned how to replace Ford O2 sensors from great info from NTK technical department and direct examination of the vehicle. Ford schematics were not much help.
Bank 1 Sensor 2 on a \'02 Ford Escape XLT is the downstream catalytic monitor sensor, located left of the Bank 1 catalytic converter (toward passenger side when looking at the car from the front) on the exhaust pipe extending from the cat. It is the easiest of the four individually colour coded sensors to remove and replace. You can see B1S2 (has a blue cable) by crouching or lying down below the front bumper and peering up from under the left front bumper splash guard (passenger side and left of the motor mount). It\'s right there mounted vertically on the pipe with blue cable wire. Can\'t miss it. The B1S2 harness connector is just right of the motor mount, right next to the O2 sensor harness. The other three sensors are very difficult tasks. I\'ll explain how to find and replace the two O2 sensors, Banks One and Two, as best as possible.
The Ford Escape XLT has four uniquely different and incompatible upstream and downstream, per catalytic, sensors. All differently coloured sheathed wires. The correct sensor must be installed at its intended location.
Bank 1 (Vehicle front)
Open and prop the front hood. Stand front centre, look straight down between the radiator and engine block (there\'s a molded coolant hose partially in the way). You\'ll see down toward the bottom, or should, a green sheathed wire and blue sheathed wire. The green is the O2 sensor. Blue is the downstream B1S2 cat monitor. You should now know the general vicinity of both sensors. Time now to get under the front end and get dirty.
Removal and replacement of O2 sensor requires removing the front bumper splash guards with 10mm socket or at least enough hex bolts removed to peel both panels off to the side and get the impeding plastic out of the way. Don\'t need ramps or garage hoist or jack. All work can done lying on your back with car in park, negative battery terminal disconnected, parking brake engaged, big empty swear jar in arm\'s reach and plenty of coins.
The right-hand method. With the guards out of the way, lying on your back, feet at the left front, relocate and follow the green cable. One end goes to the harness; other goes to the B1 cat sensor mount. Wait till car has cooled before doing this, exhaust pipes and sensor are hot enough to burn the skin. The O2 sensor is mounted at the top of the B1 cat. The cat is an upright unit, between and easily distinguishable from the manifold and exhaust pipe. The O2 is mounted near horizontal and pointing out toward the left front. Upon locating, douse it with penetrating oil and wait a few minutes to take effect. Lying on your back, feet at the right front, head toward left front, with right hand you can follow the green wire along to and eventually see, with proper light, the sensor through the hoses. Getting a wrench in there is the difficult part. This is a frustrating job even for mechanics.
The job can be done with an ordinary 7/8" spanner at an angle. But best done with the 3/8" drive L-shaped specialty O2 socket (3/8" drive mounted off to the side), unlike the standard side-slit 7/8" with centre hole 3/8. Places like Autozone sell or rent them for free with redeemable deposit. The whole objective is to turn the sensor thread a smidgen - just enough to loosen the thread seal so the rest can be unscrewed by hand. Reverse the procedure for torquing in the new one.
The best way to remove the O2 sensor, I find, is to reach up through the hoses and snug the L-shaped 7/8" specialty socket over the sensor hex head, again following the cable to accommodate the slit over. It\'s difficult, but once snugged atop, reach up the 3/8" ratchet handle with swivel extender and snap it to the socket. A stubby ratchet handle is best (there\'s next to no room to move a typical 3/8" ratchet without swivel). Snug the socket on good, click back the ratchet (have to hear that one click or two to know locked and ready) and give it a good counterclockwise pull. Not much room to do this, maybe an inch. If successful, you can feel the thread break loose. If not, keep trying (th alternative is taking to an auto shop and paying $100s in labour). Make sure the socket is snug, tension the ratchet and get that one good pull. It\'ll eventually go. Just have to find the room to maneuver the handle and why the swivel is a big help.
Once off and removed and then disconnecting the harness (the existing quick disconnect can be very troublesome), gunk dielectric grease in the new sensor harness pins. Reach by hand and thread the new O2 sensor into the hole, which you can see by eyeshot. This is tedious because it\'s an off-angle hole and difficult to mate the threads. Takes a few tries but you\'ll lock it in. Hand screw to snug, then with the L-shaped socket, torque tight a half turn. Snap the connector in till you hear the click. Done deal. Saved yourself $150-200.
Bank 2 (rear engine block)
With hood open and propped, standing on the front passenger side, look down between the firewall and rear engine block. You\'ll see, or ought to, a white sheathed cable and its connecting harness. That\'s the Bank 2 oxygen sensor. Or B2S2. Follow the white cable to the engine block to feel the sensor. You can\'t even see it. But it\'s there and can feel it. Always standing on the right (passenger) side, carefully reach through the forest of cables, find the sensor and douse with penetrating oil, at worst guessing you\'re spraying the right location. Get the standard specialty 7/8" socket (not the L-shape), reach down through the cables and hoses and snug it on the sensor. You\'ll need a couple, if not three, 5" long 3/8" drive extensions to do this. It\'s all about distance. Follow the white cable to the sensor hex head, snug on the side-slit 7/8", crank loose, un-thread, remove, discconect the harness (will probably put up a fight). Gunk dielectric grease in the new B2 O2 sensor, hand screw to snug, torque down a half turn, snap the connector in to hear the click. Hand overflowing swear jar to wife. Job well done.
Posted on Apr 22, 2014
B1 means the sensor is located on the same bank of the engine that has the #1 cylinder. B2 is located on the opposite bank.
S1 means the sensor is located BEFORE the catalytic converter
S2 means the sensor is located AFTER the catalytic converter
You didn't say which engine you have, so I've included the diagrams of both 4 cyl and 6 cyl so you can see the banks
Posted on Oct 20, 2009
sensor two is behind the convertors if you have a four cyl its the only sensor behind cat if its a 6 cyl then the side of engine closest to firewall is bank2
Posted on Jul 23, 2009
assueming it has the v-6 in it look at the exhaust pipe comming off the side of the engine there will be two up stream 02 sensors which are heated and one downstream past catalitic conveter. If may have the second style with the Y cross over with 1 upstream before the cat and one after. The difference between the 0-2 sensors is the upstrean are heated so it goes into closed loop faster. I find that on most of these the up stream 02 sensor heaters have failed. You can go to a Autozone and they can pull the codes for you and tell you which side it is that needs to be replaced. However 02 sensors get old after time and they start shifting slowly, if it shifts slowly then it's called a lazy 02 sensor. And will send a code to the computer, if you get the trouble code of the 02 sensor heater is bad you will have to change it, I recommend Replacing both. The reason is if one is going bad the other will soon follow. You can buy a socket wrench For the 02 sensors for 12 dollars makes it real easy to replace the 02 sensors when they are COLD. Hope this helps and thanks for using fix-ya.
Posted on Sep 14, 2010
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The oxygen sensor are just refered to as upstream for the o2s and down stream are actually refered to as catalytic monitors. So if you have lean or rich codes these would refer to the upstream .
Posted on May 30, 2010
Hello! I am sending two diagrams...#1 is O2 sensor location and #2 is a vacuum diagram...Before you spend a lot of money replacing O2 sensors lets eliminate other possible causes of heater circuit failure...O2's have heater circuits to bring them up to high temperature quickly so the computer (PCM) will have close control...I would suspect poor grounding, or connector contact corrosion...If you have an ohm meter...Set it on the X10 scale...Measure from center of the negative battery post to the chassis (bare metal)...And then to the engine block...Record both readings...Radio Shack sells a no-touch contact cleaner called DEOXIT...Spray a very small amount on all O2 connectors (male and female)...Oxidation is chemically removed...Re-connect...
Check all vacuum lines for broken, cracked, loose or collapsed...Send results....Guru...Saailer
I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867
Posted on Sep 10, 2010
Tips for a great answer:
Fig. Fig. 3: Oxygen sensor-4.3L engines
Fig. Fig. 4: Oxygen sensor-5.0L and 5.7L engines
Fig. Fig. 5: Oxygen sensor-7.4L engines
Oxygen sensors are always numbered like this:
Bank 1 sensor 1
Bank 2 sensor 1
Bank 1 sensor 2
Bank 2 sensor 2
Some manufacturers use a kind of shorthand that reads different, but means the same thing:
Sensor 1/1 or O2s 1/1
Sensor 2/1 or O2s 2/1
Sensor 1/2 or O2s 1/2
Sensor 2/2 or O2s 2/2
Bank 1 is always the side of the engine where cylinder number 1 is located and, of coarse, Bank 2 is the opposite side.
On a 4 cylinder engine, there is only 1 bank and it is always referred to as Bank 1.
Sensor 1 is always the upstream sensor (the one located BEFORE the catalytic converter)
Sensor 2 is always the downstream sensor (the one that is located AFTER the catalytic converter.
Hope helps (remember to rate this).
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