help anyone - Error Code P0141

[Anonymous]

My CEL light has come on, so I took it to the Toyota Garage and after the diagnostics had been run, they told me it was Error Code P0141 which they described as an Oxy Sensor which is on Bank 1 Sensor 2. They said it would increase my fuel consumption and affect the responsiveness of the car.

Anyone had simular problems? is it the O2 sensor or can it be something else?

Can anyone help and give me detailed descriptions and photos, of how to change the sensor, as I don't want to pay what the dealer wants to charge!!

thanks

Gareth

[dreambackup]

I had it (and I am not the only one, just as if it is some kind of typical problem).

it's actually (one of) the O² sensor and you'll have to change it. it seems there are sources from Denso for cheap generic O² sensors but I can tell exactly the reference.

I had mine changed under warranty...  s8) s8)

[Anonymous]

http://www.gendan.co.uk/product_O24WIRE.html

there you go.you will have to cut the existing one off and wire the new one in but you get everything required in the kit.only took about 15/20 minutes to change.
you will need a sensor removing tool as well.if memory is correct halfords sell them but im sure somebody will be along and point you to a cheaper source on the net.

[Anonymous]

Thanks for the quick replys guys!

the stealers wanted about £300 for the job! sounds like it can be done a little cheaper.

regards

gareth

[dreambackup]

genuine OEM parts are always more expensive and Toyota is no exception. I've read about an american charge $700+ for the job...  s:shock: :shock: s:shock:  

more over, Toyota told me they changed the 3 O² sensors when I had my CEL w/ P0141... that would explain a bit the 300£ they ask...

[Anonymous]

Denso product:
http://www.densoproducts.com/resultsApp.asp

For info, Celica 2ZZ has the same sensor as ours.  i use one!

[GSB]

I'm a little shocked that no-one has diagnosed this one properly yet, its got to be one of the most common Engine managment faults on this car...

Basically, Dont panic... This really isnt a problem...

The P0141 code is an advisory code, it has no effect on the actual running of the engine. Here, for the beneift of anyone who may happen to find the search button in the future, is why...

The code refers to what we call the 3rd O2 sensor, but is more accuratley called bank 1, sensor 2. There are 2 other O2 sensors on the engien, known as Bank 1, Sensor 1, & Bank2, Sensor 1. These 2 are responsible for measuring the fuel air mix that has just been burnt and exhausted by the engine. There are 2 of them because Toyota's ECU actually runs this engine as 2 seperate entities, i.e. it treats it as 2 two cylinder engines. Wierd, but effective.

The 3rd O2 sensor is fitted downstream of all the cats, wheras the 2 metering O2 sensors are fitted upstream so that they can measure the raw, un-catalysed gas coming out of the engine. Its only job in life is to measure the O2 content of the exhaust gas after the cats. The ECU then compares this reading to the one it took from the Bank 1 sensor in the manifold.  The logic it then applies to the 2 readings is astoinishingly simple:

If the 2 readings are different, and more importantly the reading from the  3rd O2 sensor is more stable than that on the manifold O2 sensor, then all is well with the world. It means that the ECU knows your cats are working as they hasve changed the make up of the gas.

If the 2 readings are the same, then the ECU knows that the cats are doing nothing to the gas at all, and lights the CEL, which prompts you do go and have your wallet lightened by your local dealer...

Becasue theres no effect on the closed loop control of the Fuelling, the engine managment makes no changes tht would effect power, or economy.

You dont actually have a failed O2 sensor though, I'd bet good money that if I hooked up my OBDII reader to your car, I'd see sensible readings coming from the 3rd O2. what you actually have, is a failed heater element.

Each O2 sensor has a built in heater inside it. The heaters are used to get the Zirconia mesuring sensors inside them up to operating temperature quickly so that they can get on with the job of measuring oxygen. This gains vital seconds in the process of gaining efficient emissions control on a cold start of the engine. Once the engine is hot, clearly anything in the exhaust flow is'nt going to be in need of heaters! The ECU monitors these heaters by measuring the current going to them, to much or too little flags up the fault code you have at the moment. The sensor itself is still working, it just takes a while to warm up... Again, having a duff heater in an ptherwise functional 3rd O2 sensor wont cause any problems with engine managment.

So, what to do to fix it? Well, you can replace the unit, or you can ignore it... Either way your car will go just as fast as its always done, using exactly the same amount of fuel. The problem with just leaving it, is that with the engine light already lit, you wont see any new problems should they occur. Fixing the thing is expensive, especially considering all you are going to gain is clear dashboard.

I appplied a bit of electrical tom-foolery to mine when it went, I simply connected a high power resistor to the heater circuit on the sensor, so that it drew the "correct" amount of current from the ECU, That way ,as  far as the ECU was concerned, the heater was working, and after 2 full start -warm up - drive -stop- cool down cycles of the engine, the light goes out. Simple...

[dimwit]

Iapplied a bit of electrical tom-foolery to mine when it went, I simply connected a high power resistor to the heater circuit on the sensor, so that it drew the "correct" amount of current from the ECU, That way ,as  far as the ECU was concerned, the heater was working, and after 2 full start -warm up - drive -stop- cool down cycles of the engine, the light goes out. Simple...

Grant, was that electrical thingy you done, also known as a 'conditioner'   s:?: :?: s:?:

[GSB]

Iapplied a bit of electrical tom-foolery to mine when it went, I simply connected a high power resistor to the heater circuit on the sensor, so that it drew the "correct" amount of current from the ECU, That way ,as  far as the ECU was concerned, the heater was working, and after 2 full start -warm up - drive -stop- cool down cycles of the engine, the light goes out. Simple...

Grant, was that electrical thingy you done, also known as a 'conditioner'   s:?: :?: s:?:

No, I just put a resistor in to simulate the presence of the heater in the sensor, the sensor itslef is still functional. A conditioner applies a signal that simulates both the heater, and the signal for oxygen content, allowing you to remove the sensor completely if required, and fool the ECU into believing that you still have cats in your exhaust when you've ripped them out.

[philster_d]

I have had this heater circuit error after we took of the H+S (thanks Tommy for reading the code)

Any more details on the resistor and where to put it would be appreciated.

/Philster

[kanujunkie]

Phil as far as i'm aware the resistor is a 20 Ohm 10-15 watts

[GSB]

I have had this heater circuit error after we took of the H+S (thanks Tommy for reading the code)

Any more details on the resistor and where to put it would be appreciated.

/Philster

I cant remember the exact value without looking up the tolerances in the BGB, but its got to be able to dissipate about 20 watts. All you do is chop the 2 black wires off of the O2 sensor, and then crimp the resistor in the wires that lead back to the car. Reset the ECU, and the fault will clear.

[Anonymous]

I recently replaced my post catalyst O2 sensor with a Universal one from here:
http://www.fpuk.co.uk/products/lambda.htm
After fitting it it seemed to work fine however the P0141 DTC triggered after a hot restart.  On the second trigger the MIL (CEL) illuminated.  This goes out after 5 cold starts.

I have plugged in my Generic Scantool and watched the sensor readings but the DTC triggers before the sensor get hot enough to work.  The ECU appears to switch the heater off after this.

I have also measured the heater resistance of the FPUK sensor and it is about 4.3Ohms compared to the 13.3Ohms of the other (pre cat) sensors.  I would doubt that the ECU can detect the exact resistance difference between the sensors and if this was the case the DTC would permanently be set.  (Note this DTC would also set if you disconnected the sensor, but this is another failure condition)

I spoke with FPUK and they said that the heater is of a lower power output than the standard OEM one.  This could cause the ECU to detect a fault due to the sensor not reading the correct value in time (Not getting hot enough).  It is possible that the Toyota bods set this trigger condition to meet US legal requirements instead more expensive methods.

For people with standard OEM parts, this could be a sign that the lambda sensor heater is faulty.  First action would be to measure the resistance of the sensors heater.  Two Black wires at the connector.

I still haven't fixed it yet.  MrT's want £156 for an OEM one!.

[GSB]

I have also measured the heater resistance of the FPUK sensor and it is about 4.3Ohms compared to the 13.3Ohms of the other (pre cat) sensors.  I would doubt that the ECU can detect the exact resistance difference between the sensors and if this was the case the DTC would permanently be set.  (Note this DTC would also set if you disconnected the sensor, but this is another failure condition)

The ECU doesn't measure resistance directly, but measures instead the current. If the resistance is to high, or open circuit (unplugged) it measures a low current and indicates a fault. If the resistance is to low, or short circuit it measures a high current, and flags the same fault.

You can cure your fault by adding a 10 Ohm high power resistor into one of the black leads on you replacement O2 sensor. Cost, around 40 pence...

[spit]

Phil - if you go with this fix, mount the resistor somewhere where it can dissipate its heat - even a high power resistor with a heatsink (RS do some nice ones!) gets v hot.

[crankshaft]

Hi;

I found this thread after searching "sensor resistor" and after reading several recent threads in the past regarding the 02 heater sensor failure, have come to the conclusion that like the precats, the only purpose is during the initial cold start ?!

So as mine is a 2001 (< 20K) I figure that like the pre-cats it's only a matter of time before they go, so maybe I should fix them before they do !

I'd like to pre-fix all 3 sensors, and would prefer to use the highest value resistor and therefore least current that is required, however I have seen that people have used between 10 and 20 ohm resistors to simulate the heater element, and was wondering if anyone knows what current the real heater elements actually draw ??

All 3 heater elements at 10 ohms would be about 4 amps, which is a bit of a waste if it's not being used !!

Any feedback greatfully received !!

Thanx

PeterC

[Anonymous]

Mine has come up after the accident repair, is there anyway this can be attributed to the accident?

[markiii]

yup

impact could have damaged teh cable

[spit]

Déja Vu!

Peter, Stock heater is 14 ohm give or take

So a 15R resistor is fine.

Seems to be pot luck on what works and what doesn't power-wise, but i don;t think any of us have experienced a problem with anything >=10W.

[Anonymous]

yup

impact could have damaged the cable

Anyway i can prove this?

[markiii]

well look at it this way the 3rd 02 sits in teh cat at teh back of teh car. the o2 sensor cable is attached to the car by clips

an impact will move the cat rather hard, the 02 wire is then going to be pulled, which could snap or stretch teh wire causing yoru problem.

prove, maybe not, but it's reasonably likely

it could also have been damaged if removed durign the repair, thats equally likely.

[crankshaft]

Thanx Spit, Hmmm, just googled and found this:

P0141     Oxygen Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)
When oxygen sensor heater operates, heater current exceeds 2.35amps (2 trip detection logic)

This indicates that the P0141 error is attributed to a heater short, i.e. excessive current, I wonder if it is the same error for an open circuit

So does the sensor normally fail 'shorted' ?? - sounds unlikely as it would almost certainly pop a fuse ?!

Unfortunately I can't test it until I am back in the UK in a few weeks, but I am going to try using a 47R as well as a 100R just to see what happens !

PeterC

[Liz]

Does no one ever check out the links at the top of the forum - we have a full list on there:

 m http://www.mr2roc.org/subdreamer/index. ... rticleid=8 m

[spit]

Yep, the full code list is in articles Peter, but not the detail you're looking for I suspect.

I think its just an open circuit that triggers the CEL, but this is way beyond my brain now  s:oops: :oops: s:oops:

Be interesting to see how tolerant the circuit is to different loads - I was thinking of using the supply for some nice neons  s:lol: :lol: s:lol:    s:wink: :wink: s:wink:  

*hunts around for his chav baseball cap*

[crankshaft]

Hi Liz,

Urmm, Thanx we know what the failure code is, we are trying to deterimine how to avoid it pre-emtively !

Cheers

PeterC