Don~
Yep. Right on the money. 100K is the expected lifespan of the heated air-fuel/oxygen sensor.
It's a fairly straightforward remove/replace IF you don't have a heavily rusted exhaust manifold and the unit isn't seized in place. It is the front, driver's side sensor throwing the code. If you can change out spark plugs, you can do this and save yourself some $$$. A substantial percentage of this service bill at the dealer is labor, on top of which they also gouge you on the sensor units themselves. I've removed and reinstalled all four of mine just to inspect and get a good application of anti-seize on them.
Note that when one side goes, the other side is probably not far behind. I strongly suggest you replace both banks while you're already under there. Why pay shipping twice? My $0.02.
For your 2001 Tundra V8 SR5 4X4:
Here is the sensor you need: Denso, #234-4169. Amazon has em for about $40. Both sides take the same one. (first pic, below) Resist the impulse to try a cheaper aftermarket or other brand part here. This is an ECU-related component, and you'll have problems, guaranteed. I'd also steer clear of the "universal" models that require you to resplice the wiring into the old connector. Just to save a few $$$? On a component that should last another 100,000 miles?
You will also need a specialty socket that has a cutout to allow you to work around the attached wires. Your local auto parts supply should have one in stock. There are a couple different styles. I've seen them at Harbor Freight for about $5 as well. (fourth pic below)
The upstream sensors are located under the rearward end of the exhaust manifold, just forward of the exhaust pipe flange. For best access, lay with your head facing towards the front and reach back and over the front crossmember. I have a 2" lift and I don't even need to jack up the truck to do this. You can remove the skidplate to facilitate the procedure, although it isn't necessary. (see the fifth pic below for a view of this sensor)
Give the base of the sensor a good soaking of PB Blaster, WD-40, Kroil or some other penetrating lube and let it sit overnight. As you are working at the exhaust manifold, I suggest you do the R/R on a COLD engine. It is also to make sure that the manifold is not in an expanded state from heat. Chilton suggests that if the sensor is hard to remove, you might want to start and run the engine for a minute or so, shut it off, and try it again. Be careful! The sensor, manifold, and exhaust will all be HOT! Be especially careful of the intake tube end of the sensor... the inside gets heated to 1500F!!
Then, the steps to remove and replace are:
1. Unplug the wire harness connector.
(It is gray, and will be up about 7" or so from the sensor. You might try using a small screwdriver to push down on the little retaining tab so the connector half will slide out. Take your time here. It can be a little finicky. This part took me longer than the actual sensor to remove.
* * * SUGGESTION * * *
For those with really gummed up upstream O2 connectors, you might try cleaning one of the rears first with some CRC MAF Cleaner and practice disconnecting one of those so you can see how they are configured; they are WAY easier to access. Trying it blind reaching up on the manifold is a pain.)
2. Get the sensor socket on it and remove.
This can be tricky. Try using different length socket extenders, if needed, to assist with the reach {thanks to RocketChild for the tip!}. A seized sensor is NO fun. Use the PB Blaster liberally. Start to unscrew the sensor, and if you get serious resistance, hit the threads with the lube and then screw it back in. Do this a few times; it should work its way out. If it doesn't, I'd suggest letting the dealer or a trusted local shop do the work. Some people feel comfortable putting a breaker bar on it to get it loose, but it is my opinion that you don't want to be at home with stripped out manifold threads. If this happens, I'd bite the bullet and invest in some JBA or Doug Thorley headers anyway and call it a day.
3. Apply anti-seize compound (available at your local auto and marine supply stores, see pic below) to the threads of the new sensor. Denso normally includes a little tube of it with their sensors. There are only about 3 or 4 threads on these units, so just use a little and make sure to keep any compound away from the sensor's input ports. I'd also apply a very thin film on the seating surface as well.
4. Carefully start threading the unit in by hand. Take your time. They're in a position that is hard to see.
(Just like spark plugs, you do NOT want to cross thread these.)
5. Apply the sensor socket carefully to the sensor.
(Make sure you do NOT get the wires bound up.)
6. Torque to specs. (TSM states 32 ft/lbs. I think this is a little high, especially with the anti-seize, so I torqued mine to about 20-22 ft/lbs. Your call.)
7. Reconnect the wire harness connector(s).
8. To clear the code (if any), either get a OBDII-compliant code reader or disconnect the negative terminal on the battery for half an hour or so to drain all residual system/ECU memory, reconnect, and drive. The code should be gone.
Done. :nod:
Do not skip the step of using the anti-seize. Sometimes you will get a package with your sensor unit. Sometimes not. A tube is only about $6.
Note that if you can get these done by yourself, when the time comes to do the same to the downstream (BX/S2) ones, they are WAY easier. They are a little more expensive. On the 2000-2004 model years, you don't need the O2 socket, but the TSM suggests you replace the metallic gasket and mounting nuts. (second pic below, location view on the last pic below). The 2005-2006 4.7L model years' downstream sensors thread into the cat directly just like the fronts.
Also note that on some model years of 4WD Tundras, there are different model number specifications for the rear sensors than with the 2WD models. It is the same sensor but one side has a little longer wiring harness to account for driveline geometry of the 4X4. Crosscheck carefully to assure the right sensor for your truck.
Let us know how it went for you. :tu:
- Remmy700P
* * * A Note About Oxygen Sensor Wire Harnesses * * *
Oxygen sensors thread into the exhaust system where they face extreme heat, violent impacts from road debris, and harsh exhaust gases. One reason oxygen sensors fail is when the sensor bulb inside is exposed to lead, silicone, antifreeze, engine oil and other contaminants. But, many people are not aware of the role that the other end of the oxygen sensor plays. Surprisingly, the visible end of the sensor with the wire pigtail is just as important and sensitive to contamination as the end slugging it out in the exhaust pipe.
Combustion engine vehicle oxygen sensors are designed to measure the difference between the oxygen level in the exhaust with the oxygen level in the outside air. The sensor generates a voltage based on the difference in oxygen levels that the ECU uses to continuously adjust the fuel mixture, etc. The outside air the oxygen sensor needs for its comparison enters the sensor at the end with the wire pigtail. Depending on the sensor design, the air might enter through a dedicated hole on the connector or through the wires themselves.
The oxygen sensor ambient air inlet is likely to be protected by silicone boots, porous PTFE (Teflon) or some other means. A routine splash of water is not likely to hurt an oxygen sensor, but leaking chemicals (engine oil, power steering fluid, etc.) can clog or enter the oxygen sensor air inlet and damage the sensor. Efforts to “protect” oxygen sensors by spraying them with lubricant, covering them with insulation, etc. can backfire if the sensor’s air inlet is blocked or contaminated.
Oxygen sensor installation instructions emphasize that the entire sensor, including the wiring harness, is part of an integrated system. Routing and connecting the wires is as important as carefully threading the sensor into the pipe.
Yep. Right on the money. 100K is the expected lifespan of the heated air-fuel/oxygen sensor.
It's a fairly straightforward remove/replace IF you don't have a heavily rusted exhaust manifold and the unit isn't seized in place. It is the front, driver's side sensor throwing the code. If you can change out spark plugs, you can do this and save yourself some $$$. A substantial percentage of this service bill at the dealer is labor, on top of which they also gouge you on the sensor units themselves. I've removed and reinstalled all four of mine just to inspect and get a good application of anti-seize on them.
Note that when one side goes, the other side is probably not far behind. I strongly suggest you replace both banks while you're already under there. Why pay shipping twice? My $0.02.
> > > > For the correct sensor, go here: Denso part lookup page < < < <
For your 2001 Tundra V8 SR5 4X4:
Here is the sensor you need: Denso, #234-4169. Amazon has em for about $40. Both sides take the same one. (first pic, below) Resist the impulse to try a cheaper aftermarket or other brand part here. This is an ECU-related component, and you'll have problems, guaranteed. I'd also steer clear of the "universal" models that require you to resplice the wiring into the old connector. Just to save a few $$$? On a component that should last another 100,000 miles?
You will also need a specialty socket that has a cutout to allow you to work around the attached wires. Your local auto parts supply should have one in stock. There are a couple different styles. I've seen them at Harbor Freight for about $5 as well. (fourth pic below)
The upstream sensors are located under the rearward end of the exhaust manifold, just forward of the exhaust pipe flange. For best access, lay with your head facing towards the front and reach back and over the front crossmember. I have a 2" lift and I don't even need to jack up the truck to do this. You can remove the skidplate to facilitate the procedure, although it isn't necessary. (see the fifth pic below for a view of this sensor)
Give the base of the sensor a good soaking of PB Blaster, WD-40, Kroil or some other penetrating lube and let it sit overnight. As you are working at the exhaust manifold, I suggest you do the R/R on a COLD engine. It is also to make sure that the manifold is not in an expanded state from heat. Chilton suggests that if the sensor is hard to remove, you might want to start and run the engine for a minute or so, shut it off, and try it again. Be careful! The sensor, manifold, and exhaust will all be HOT! Be especially careful of the intake tube end of the sensor... the inside gets heated to 1500F!!
Then, the steps to remove and replace are:
1. Unplug the wire harness connector.
(It is gray, and will be up about 7" or so from the sensor. You might try using a small screwdriver to push down on the little retaining tab so the connector half will slide out. Take your time here. It can be a little finicky. This part took me longer than the actual sensor to remove.
* * * SUGGESTION * * *
For those with really gummed up upstream O2 connectors, you might try cleaning one of the rears first with some CRC MAF Cleaner and practice disconnecting one of those so you can see how they are configured; they are WAY easier to access. Trying it blind reaching up on the manifold is a pain.)
2. Get the sensor socket on it and remove.
This can be tricky. Try using different length socket extenders, if needed, to assist with the reach {thanks to RocketChild for the tip!}. A seized sensor is NO fun. Use the PB Blaster liberally. Start to unscrew the sensor, and if you get serious resistance, hit the threads with the lube and then screw it back in. Do this a few times; it should work its way out. If it doesn't, I'd suggest letting the dealer or a trusted local shop do the work. Some people feel comfortable putting a breaker bar on it to get it loose, but it is my opinion that you don't want to be at home with stripped out manifold threads. If this happens, I'd bite the bullet and invest in some JBA or Doug Thorley headers anyway and call it a day.
3. Apply anti-seize compound (available at your local auto and marine supply stores, see pic below) to the threads of the new sensor. Denso normally includes a little tube of it with their sensors. There are only about 3 or 4 threads on these units, so just use a little and make sure to keep any compound away from the sensor's input ports. I'd also apply a very thin film on the seating surface as well.
4. Carefully start threading the unit in by hand. Take your time. They're in a position that is hard to see.
(Just like spark plugs, you do NOT want to cross thread these.)
5. Apply the sensor socket carefully to the sensor.
(Make sure you do NOT get the wires bound up.)
6. Torque to specs. (TSM states 32 ft/lbs. I think this is a little high, especially with the anti-seize, so I torqued mine to about 20-22 ft/lbs. Your call.)
7. Reconnect the wire harness connector(s).
8. To clear the code (if any), either get a OBDII-compliant code reader or disconnect the negative terminal on the battery for half an hour or so to drain all residual system/ECU memory, reconnect, and drive. The code should be gone.
Done. :nod:
Do not skip the step of using the anti-seize. Sometimes you will get a package with your sensor unit. Sometimes not. A tube is only about $6.
Note that if you can get these done by yourself, when the time comes to do the same to the downstream (BX/S2) ones, they are WAY easier. They are a little more expensive. On the 2000-2004 model years, you don't need the O2 socket, but the TSM suggests you replace the metallic gasket and mounting nuts. (second pic below, location view on the last pic below). The 2005-2006 4.7L model years' downstream sensors thread into the cat directly just like the fronts.
Also note that on some model years of 4WD Tundras, there are different model number specifications for the rear sensors than with the 2WD models. It is the same sensor but one side has a little longer wiring harness to account for driveline geometry of the 4X4. Crosscheck carefully to assure the right sensor for your truck.
> > > > For the correct sensor, go here: Denso part lookup page < < < <
Let us know how it went for you. :tu:
- Remmy700P
* * * A Note About Oxygen Sensor Wire Harnesses * * *
Oxygen sensors thread into the exhaust system where they face extreme heat, violent impacts from road debris, and harsh exhaust gases. One reason oxygen sensors fail is when the sensor bulb inside is exposed to lead, silicone, antifreeze, engine oil and other contaminants. But, many people are not aware of the role that the other end of the oxygen sensor plays. Surprisingly, the visible end of the sensor with the wire pigtail is just as important and sensitive to contamination as the end slugging it out in the exhaust pipe.
Combustion engine vehicle oxygen sensors are designed to measure the difference between the oxygen level in the exhaust with the oxygen level in the outside air. The sensor generates a voltage based on the difference in oxygen levels that the ECU uses to continuously adjust the fuel mixture, etc. The outside air the oxygen sensor needs for its comparison enters the sensor at the end with the wire pigtail. Depending on the sensor design, the air might enter through a dedicated hole on the connector or through the wires themselves.
The oxygen sensor ambient air inlet is likely to be protected by silicone boots, porous PTFE (Teflon) or some other means. A routine splash of water is not likely to hurt an oxygen sensor, but leaking chemicals (engine oil, power steering fluid, etc.) can clog or enter the oxygen sensor air inlet and damage the sensor. Efforts to “protect” oxygen sensors by spraying them with lubricant, covering them with insulation, etc. can backfire if the sensor’s air inlet is blocked or contaminated.
Oxygen sensor installation instructions emphasize that the entire sensor, including the wiring harness, is part of an integrated system. Routing and connecting the wires is as important as carefully threading the sensor into the pipe.
