TSB #TSB-0064-10
NHTSA ID #10034284
Date Announced: FEBRUARY 04 2010
Additional Info: How to Fix
Summary: TOYOTA: TECHSTREAM ECU FLASH REPROGRAMMING PROCEDURE. FLASH REPROGRAMMING ALLOWS THE ECU SOFTWARE TO BE UPDATED WITHOUT REPLACING THE ECU. FLASH CALIBRATION UPDATES FOR SPECIFIC VEHICLE MODELS/ECUS ARE RELEASED AS FIELD-FIX.
Question:
Even though the van has P0420 and P0420P (Oxygen sensor before cat and after cat, with Catalyst System Efficiency Below Threshold (Bank 1)." is it OK to keep driving it?
I don't notice any performance problems.
Will driving with the problem damage the catalytic converter or other engine components?
If you can actually bring up that TSB, you'll find that our year's ECU isn't flash-capable. I'd love you to prove me wrong though!
Someone else can chime in here about the P0420, but I'll reiterate my view there's no danger of engine damage. The downstream sensor's output solely monitors catalyst efficiency, and does not input into engine operational parameters.
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Based on the advice I've read so far, I checked the exhaust system for damage, holes and gasket leaks but found none.
However, I did noticed that the oxygen sensor *after* the catalytic converter had been replaced (must have been 5 years ago when I bought it) and who ever did the repair snapped the rusted bolts off, but used an orange adhesive to glue the replacement sensor in place.
I showed this to my friend who is a maintenance mechanic and he said it is a standard high temperature silicone adhesive that is safe to use for sensors and while not the best repair, it looks solid.
Also...
I checked all the vacuum hoses for damage or loose hoses and found none.
I looked for the Electronic Idler Valve you mentioned, but could not find it.
So, there is no danger of engine or catalytic converter damage with a P0420 and P0420P trouble code?
The oxygen sensor that has the high temp adhesive holding it in place is AFTER the LARGE Catalytic Converter under the middle of the van (Bank 1, Sensor 3).
The sensors for Bank 1 near the engine (closest to firewall) look like the originals. However, I can't figure out how to remove them as there is no room to work with all the other parts in the way.
Questions:
* How do I remove these oxygen sensors?
* Is there a special tool needed to reach them?
* Is there a way to test these sensors? and just to confirm...
* Is there any danger of engine or catalytic converter damage to continue driving with the P0420 and P0420P trouble codes?
First, "will this cause further damage?"
If you are getting codes your engine is not operating correctly. In most cases it will be running rich. Some say this will damage a cat. You need to fix the problem and there is a solution. We need to figure it out together. I've never had these problems with my 220,000 mile Sienna so it's not like it's a design flaw or something. I have noticed that most of the poster's here have 2002 or 2003. Are all of the poster's driving VVTi motors?
Anyway there are three sensors total. Two are mounted high in the manifold and the third is mounted after all of the cats. It's plug actually connects inside the van under the passenger seat. The front sensor (bank 2) is obviously easy to get to. The rear sensor (bank 1) is difficult to get to. When I change mine, which I've done twice over the years, it's a real fight. The last time I out smarted it and had my daughter plug the connectors in. Unplugging it and re-plugging is the most difficult part. I think that I used an O2 sensor socket but I may have used an open wrench. I think that either will get in there. I think I used a huge standard wrench. You can test size on the front one. The rear one must be removed from underneath the van. Space is very tight but it can be done without taking anything apart. The first time it took me over an hour but I knew I'd saved lots so I didn't care. When I enlisted my 12 year old daughter I got it done in 15 minutes.
The sensors can be tested once removed. This is basically a cat thread but there is another thread about O2 sensor codes that has all of the O2 sensor info.
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I checked the exhaust pipe for Black Soot, which is a sign of an engine running too rich and it looks normal.
The van is running strong with no issues or loss of MPG.
So it sounds like changing the sensors (or at least taking them out and testing them) is the first thing to do.
I found this diagram on the AutoZone website with the location of the sensors... http://img192.imageshack.us/i/2002si...nsorsimag.jpg/
It looks like Bank 2 Sensor 1 is on top, closest to the firewall.
I put the van up on ramps and looked underneath, but can't see it.
Do I have to remove any parts to get to these sensors?
Thanks!
Last edited by RallyxB; 01-11-2011 at 01:29 PM.
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That diagram is totally tripping me out. I'm pretty sure there are only three sensors total. The diagram is also for a V8.
To get to the sensor on the back of the motor:
First put it up safely. Slide under there until you are looking up the firewall. There will only be about three inches of clearance. It's up in there. It will be an epic battle between you, power steering parts, the sub-frame, and other awesome things. You just have to get up in there. I couldn't really figure out how to get two hands to the connector at one time. I had my daughter plug it back up.
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* UPDATE *
The check engine light came back on after 150 miles.
I bought a Haynes Repair Manual for reference and it describes the sensors closes to the engine... "On all 2001 and later models the upstream sensors are Air/Fuel sensors and the downstream sensor is a heated oxygen sensor." and that "like an oxygen sensor, the A/F sensor has a heating element."
So technically it's an Air/Fuel sensor?
How long are these sensors supposed to last?
The book also details a procedure on how to test the sensors, but it says to use a "specially slotted socket" to remove the sensors.
Does anyone know where I can get a slotted-socket and what size?
They generally last until you get a code. My first one failed at 80,000 miles and the second one at 200,000 miles. The third downstream sensor is original to the best of my knowledge. I don't know that you can get one of those socket things on the rear one. I know that I just used a big wrench on it. The O2 sensor socket tool is a universal size, meaning that all of the sensors are the same size.
I replaced all three o2 sensors on our '98 Sienna at 260,810, after getting the P0420. We're now at 284,000+ and all is well. I borrowed an o2 sensor tool kit from Advance Auto--actually, they sell it to you but then give you a refund when you bring it back. The sensor removal kit came with three different types of wrenches so hopefully you'll find one to fit your situation. NOTE: PB BLASTER is your very best friend when removing these sensors. Also, be sure to check www.rockauto.com before buying any sensors -- I saved a lot of money, paying about $40 per sensor (I used Universal Denso sensors and I realize my '98 has a different sensor than the newer vans which have A/F sensors).
Black Sunshine is right (as always!) - the sensor on the firewall side of the engine is tough to put a wrench on, but if you are stubborn and take your time, you'll get it. In fact, I had more trouble with the wiring than I did with the sensor removal because the in-line wiring plug is out of reach. Since I was using universal sensors that required butt-splicing the wires, I was able to replace the sensor without having to figure out how to reach the in-line plug which is down along the firewall and out of my reach. I have another post on here somewhere that describes that at length.
Good luck!
The Following User Says Thank You to TierOneSupplier For This Useful Post:
Thanks Gang! Lots of good information here! Great place to start.
I have a '98 Sienna with 175,000 miles & it runs like a top. I just keep fixing the minor issues & it keeps me happy. I have 3 kids so they have pretty much stained all the interior.......... but those Japanese parts............. they never ware out!
I have the PO420 code but the car runs fantastic! I'm getting even better mileage since the code came on. Previously the engine ran rather rich & I could smell raw fuel out the exhaust. Now, not so much. There is no air/fuel mixture screw like my old carburetor............. so I was kinda bummed. Since it's not running poorly now I know the catalytic converter is not plugged. The mechanic said 9 times out of 10 it's the CAT but @ $320 installed, of course he said that.
So my next trip is to autozone! They rent the slotted socket there. They also want over $100 for each sensor. Thanks for the pics & info. Oxygen sensors & socket kit & PB Blaster. I'm going to take my time fixing it since I'm getting much better gas mileage now!
I replaced all three o2 sensors on our '98 Sienna at 260,810, after getting the P0420. We're now at 284,000+ and all is well. I borrowed an o2 sensor tool kit from Advance Auto--actually, they sell it to you but then give you a refund when you bring it back. The sensor removal kit came with three different types of wrenches so hopefully you'll find one to fit your situation. NOTE: PB BLASTER is your very best friend when removing these sensors. Also, be sure to check www.rockauto.com before buying any sensors -- I saved a lot of money, paying about $40 per sensor (I used Universal Denso sensors and I realize my '98 has a different sensor than the newer vans which have A/F sensors).
Black Sunshine is right (as always!) - the sensor on the firewall side of the engine is tough to put a wrench on, but if you are stubborn and take your time, you'll get it. In fact, I had more trouble with the wiring than I did with the sensor removal because the in-line wiring plug is out of reach. Since I was using universal sensors that required butt-splicing the wires, I was able to replace the sensor without having to figure out how to reach the in-line plug which is down along the firewall and out of my reach. I have another post on here somewhere that describes that at length.
Good luck!
Can you show me where to buy these three sensors? Are they identical? All 3 of them? Do they have a cheaper universal version where I could splice the wires without having to remove the contact ( is this recommended?
I bought my sensors at www.rockauto.com for about $40 each (plus shipping). They were the universal sensors. The Denso part number is 234-4209, which is for the '98 Sienna. Later model years use a different part, but for the '98, the same universal sensor is used in all three places. As soon as I replaced all three sensors, the P0420 was gone.
It seems the only difference in sensor part numbers for the '98 Sienna is the length of the wiring harness, because at the time, the same universal sensor was called out by Denso's web site (see the link, below) for all three sensors.
To your last question, yes, the original electrical connector is kept in service when replacing the sensor with a new "universal" sensor. The universal sensor is sold with a butt splice kit. Somewhere here on TN I posted a detailed description of how I did it. Your biggest challenge will be keeping the butt splice connection free of moisture.
Interestingly, I didn't see the 234-4209 on RockAuto this morning. Maybe out of stock? Do a web search on this site, http://www.densoaftermarket.com/first-time-fit.php
to find the specific application for your vehicle, and to see if the 234-4209 is still available.
If you have any more questions, of course chime in!
I bought my sensors at www.rockauto.com for about $40 each (plus shipping). They were the universal sensors. The Denso part number is 234-4209, which is for the '98 Sienna. Later model years use a different part, but for the '98, the same universal sensor is used in all three places. As soon as I replaced all three sensors, the P0420 was gone.
Interestingly, I didn't see the 234-4209 on RockAuto this morning. Maybe out of stock? Do a web search on this site, http://www.densoaftermarket.com/first-time-fit.php
to find the specific application for your vehicle, and to see if the 234-4209 is still available.
If you have any more questions, of course chime in!
Mine is a 2002. Do you think it uses different part or the same one ?
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Rockstar
. My first one failed at 80,000 miles and the second one at 200,000 miles. The third downstream sensor is original to the best of my knowledge. I don't know that you can get one of those socket things on the rear one. I know that I just used a big wrench on it. The O2 sensor socket tool is a universal size, meaning that all of the sensors are the same size.
Lots of good information here! Great place to start.
I'm going to take my time fixing it since I'm getting much better gas mileage now!
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