O2 sensor replacement?

Anonymous · December 1, 2004, 18:39

Whilst driving to work a few days ago I noticed an orange engine warning light had appeared. Although nothing seemed wrong I pulled over and gave the car a quick once over before continuing to work.

I had it checked out and was told that my oxygen sensor was faulty and the car was currently running in safe mode. I'm just out of warranty and the car has done 21,000 miles so the failure seemed somewhat premature to me. Especially when I was informed that it would cost me £214 to replace it. When I had recovered I informed the service guy that the car would need to remain in very safe mode until after the christmas period i.e. in my garage!! after all I have a ski trip to pay for!

My question is does anyone know the spec/part number and where I can purchase a replacement sensor? Bosch, Denso? After reading other related posts I have one price from Gendan of £144. Any other options?

Also (I've not had a good look yet) but how easy is it to get at/replace and will I need a special tool?

I have read that cleaning may be an option and cycling the power to the electronics - Is this worth a try or when they say the part is faulty is it definitely faulty? This morning the light was out (may of been as a result of the garage inspections?) but came back on within 3-4 miles as I was driving up a steep incline.

Thanks in advance for any advice. s:roll: :roll: s:roll:
Simon

Slacey · December 1, 2004, 19:27

I'm sure you can buy generic O2 sensors for around £50, I'll look into it. You will need an O2 tool to remove the sensors themselves, but they are cheap and easy to get hold of, see here....

Cleaning and resetting the ECU is an option though, and is worth trying; you never know.

Tem · December 1, 2004, 19:50

Quote from: "Slacey"I'm sure you can buy generic O2 sensors for around £50

I bought a generic 4-wire Toyota O2 sensor earlier this year and it was about 50 euros (£35), so they are definitely available.

GSB · December 1, 2004, 20:17

Heres what i'd do if i were in your shoes, and needed a quick fix to :

a)avoid being burgled by Toyota,
& b)needed to have use of the car for the short period until I got a proper fix...

There are 3 O2 sensors on your car. For your car to be running in "safe mode" it has to be one of the sensors in the manifold thats failed. I would swap the failed sensor for the 3rd one that lives in the exhaust pipe after the main cat. The lead on the failed one wont be long enough to plug in when its in the 3rd O2 position, but it wont matter anyway. With the working O2 sensor from the 3rd O2 position in the manifold, the ECU will be getting the info it requires regarding fuel air mix, and once reset it will be in normal running mode. You'll still get a CEL as the ECU wont be able to read the O2 content after the cat, but thats just a warning signal and wont engage the safe mode, leaving your engine management processes almost normal.

Once you get a new sensor, you can change it at your leisure. s:wink: :wink: s:wink:

Anonymous · December 1, 2004, 23:44

Thanks for the replies so far.

I believe toyota indicated it was the O2 sensor after the CAT that was the problem but he also said I was in safe mode.

Does this tally up or is it only the manifold sensors that would cause this to happen?

Slacey if you find a lead for the aforementioned sensor I'd appreciate it - £50 seems a more paletable price to pay for a sensor.

Tem, out of interest where did you get the generic 4 wire sensor and was it for the after the CAT position? (do I take it all 3 are the same/interchangeable?)

Does anyone know how these things work? are they electrochemical?

Cheers s:P

s:P
Simon

Tem · December 2, 2004, 06:37

Quote from: "lamberts"Tem, out of interest where did you get the generic 4 wire sensor and was it for the after the CAT position? (do I take it all 3 are the same/interchangeable?)

From a local car parts store and they are all the same, only the wiring is different (and generic sensors come without wiring anyway).

GSB · December 2, 2004, 06:57

The sensor after the cat is the same as the other two, except for a longer lead. Does your car feel any different? If not, I suspect the technician was spinning you a line regarding the safe mode...

Slacey · December 2, 2004, 08:23

Here you go - check this link:

m https://www.automedicsupply.com/catalog ... 123607ae47 m

With shipping from the US the generic one (at the excellent current exchange rate) weighs in at £45. I'll keep looking to see if I can find a cheaper source.

roger · December 2, 2004, 14:26

One word of warning - getting the sensors out may be a problem.

I have a new car, the RH manifold one came out easily, the left wouldn't budge. Others have had the same problem, some have involved removing the manifold, drilling studs etc!!!!

I suggest you buy, beg or borrow the tool first and try removing them asap. Then if the worst comes to the worst and you have to go to MrT, you won't have paid out for a new sensor that they might not fit.

roger

Slacey · December 2, 2004, 17:06

It would appear that some have had O2's that were cross-threaded at the factory s:? :? s:?
Fortunately mine and the others that I have checked all came out OK, so fingers crossed....

Anonymous · December 2, 2004, 18:13

Thanks for the advice/link. Slacey I take it both of the parts listed fit the bill? I just wondered why one was down as OEM and the other Universal (at 26USD) when they are both listed the Brand as Walker ??

Where did you get the shipping cost from?

Simon

Slacey · December 2, 2004, 20:53

Quote from: "lamberts"Thanks for the advice/link. Slacey I take it both of the parts listed fit the bill? I just wondered why one was down as OEM and the other Universal (at 26USD) when they are both listed the Brand as Walker ??

Where did you get the shipping cost from?

Simon

Not sure on the OEM / universal thig, but I'd just go for the cheapest option. As for the shiiping, I 'pretended' to buy one, and went as far as the shipping page - $25 to the UK.

Anonymous · December 7, 2004, 14:27

Hi,

I was pretty sure I'd seen on here somewhere that someone had posted a link to a place that sold O2 sensors - so did a quick search and found it!

http://www.gendandirect.co.uk/viewproduct.php?product=O24WIRE

They're £35 and are made by DENSO, IIRC they make the stock O2 sensors fitted to the '2...

And for a O2 sensor socket (this is where I got mine from...);

http://www.tooled-up.com/Product.asp?PID=28519

I hope that helps...

Anonymous · December 7, 2004, 16:48

After you take the O2 sensors off and reinstall them several times, it becomes clear why a number of owners have experienced the cross-threading problem; they can be tricky to seat correctly. I recommend a touch of anti-seize compound on the threads before reinstalling, and consider painting the heat shield at this time, too.

Anonymous · December 7, 2004, 19:33

Thanks again for the advice.

Qu. Is the 4 wire sensor mentioned above from Gendan a direct replacement for the O2 sensor after the CAT?

Gendan told me they do not carry the sensor I require but can order it in for £140.

Much appreciated
Simon

Tem · December 8, 2004, 07:41

Quote from: "lamberts"Qu. Is the 4 wire sensor mentioned above from Gendan a direct replacement for the O2 sensor after the CAT?

Gendan told me they do not carry the sensor I require but can order it in for £140.

Well, the sensor itself is a direct replacement. But you have to cut the stock sensor off the wire harness and connect the new one in it's place.

For £140 you probably get a plug and play sensor with the harness.

I always put the sensors in by hand and only use the socket for the final torque. That way I'm pretty sure I won't cross thread it, which can happen pretty easily with a tool...

Anonymous · December 8, 2004, 17:41

Thanks for all the advice. Feel pretty comfortable ordering the 4 wire universal replacement now.

Cheers
Simon

s:wink: :wink: s:wink:

Anonymous · January 12, 2006, 13:39

Hi,

I've order a DENSO 4-wire 02 sensor to replace the 3rd 02 sensor which has just died on me. Does anyone have some tips about the procedure for replacing new for old?

Q. Do I have to do any cutting, splicing or soldering of wires? will it be obvious which wires go where?

Q. Do I have to remove anything to get to the 3rd sensor? (bumper, lights, etc?)

Q. Do I have to jack the car up to get at it?

Any other specialist tools needed for the job? I have a 02 sensor socket already.

Thanks

Yorkie

Slacey · January 12, 2006, 14:57

You can get to it from the engine bay, although it will be easier if you remove the bumper. Yes, you will have to cut the Toyota connector off the old one and solder to the new one - IIRC the two white wires are for the heater circuit (does anyone know if these can go any way round - I think they can), the grey is the earth and black is the signal.

Tem · January 12, 2006, 20:40

Quote from: "Slacey"two white wires are for the heater circuit (does anyone know if these can go any way round - I think they can)

Yeah, it's just a resistor, either way is fine.

spit · January 12, 2006, 22:28

Quote from: "Slacey"IIRC the two white wires are for the heater circuit (does anyone know if these can go any way round - I think they can), the grey is the earth and black is the signal.

Does the third O2 have different colour wiring to the manifold sensors then....?

Slacey · January 13, 2006, 07:14

I don't think so... I'll have a look when I get my car out of the garage later. I'm sure all three are the same though.

spit · January 13, 2006, 09:33

....or maybe its a J-Spec difference. My two manifold connectors are:

o Black: Heater supply +12v
o Black: Heater ground
o Blue: Signal
o White: Signal ground

Anonymous · January 16, 2006, 09:50

Hmm...now I'm just confused.

firstly, just a recap... My CEL came on about a week ago so the first thing I tried was resetting the ECU and cleaning the MAF as per the instructions and recommendations on this site. Not sure if it's worth mentioning but I reset the ECU by disconnecting the battery (at the positive terminal - was later told this was a dangerous way to do it!). Anyway, the battery was reconnected after 20 minutes and the clock showed 0:00 and the radio presets were lost - fair enough. CEL was not displaying...until part way through my third journey when it reappeared. Have read somewhere that the CEL will only display after the ECU reads the same fault during 3 seperate power cylces so it makes sense that the CEL would reappear on my third journey.

Moving on, I took the car to Toyota where they diagnosed a P0141 (bank 1, sensor 2) - the 3rd 02 sensor. I didn't fancy the £190 parts + labour quote from them so I ordered a universal DENSO 4-wire 02 sensor, and a sensor socket.

Over the weekend I coerced a mechanic-minded mate to help me out. We disconnected the battery (at the negative terminal), removed the old sensor, cut the wires, connected up the new sensor (making sure to get the wire colours absolutely correct), insulated the connections and installed the new sensor. When we reconnected the battery, the clock read 1:58! (it was 4pm in the afternoon), radio presets were lost though. CEL was off, but came back during my second outing - this made me suspicious. Why wasn't the clock reading 0:00 and why would the CEL come back on only part way through my second journey? Surely it should wait until the third journey at least?

I thought maybe the ECU hadn't been reset properly so I tried it again last night. I disconnected the battery (at the negative terminal), left it off for about 45 mintues, reconnected, checked the clock 1:02 - what's going on! after mulling this over for a while I thought back to how I did it before and the only difference seems to be which terminal I disconnected. So I removed the positive this time, left it off for over 3 hours, reconnected, checked the clock - 1:00!!! why doesn't it read 0:00??? I didn't drive it anywhere after last night but have driven it into work this morning, CEL was off.

My questions are:

Q. Is it possible for the ECU to somehow not reset properly, even if the battery is disconnected?

Q. Does it make a difference which battery terminal is disconnected if I'm wanting to reset the ECU?

Thanks

Yorkie

spit · January 16, 2006, 13:24

Quote from: "yorkie"Q. Is it possible for the ECU to somehow not reset properly, even if the battery is disconnected?

Anything is possible I suppose, but I haven't come across a failed reset if the power is cut s:? :? s:?

Quote from: "yorkie"Q. Does it make a difference which battery terminal is disconnected if I'm wanting to reset the ECU?

No, but disconnecting the negative (earth) prevents the likelihood of you shorting out the battery with a spanner on the positive terminal (if the neg was still connected....if you see what I mean).

I've just done a reset, and my clock kicked off at 1:00 aswell. Not noticed this before, but there is no doubt that the ECU has reset itself - idle is all over the shop s:? :? s:?