Help!, O2 sensor problem. Toyota can't find prob!

[alan.motherwell]

Hi everyone, first time I'm starting a post and it's a biggie. Are you seated? Good, we'll begin.

Last year I took my car to the garage to get fixed as it had some running problems. It would hiccup and stutter between 1500-3000rpm but if you put your foot down it was fine and it only happened when hot. They struggled to find any problem and there was no check engine light at this point. After going back to the garage several times they replaced the o2 sensors as they could not find anything else to try. This did not fix the problem and the car was sent to Toyota garage.

They had the car for 1 Month and replaced things trying to find the problem, they replaced the crankshaft position sensor, they were just about to take the head of, which was not covered by warranty and they noticed the cover of the oil control valve looked tampered with they replaced this and it fixed the problem great!!! The car had a new water pump fitted quite recently, by reg vardy, and its my suspscion they damaged it. So problem solved they test drove and it drove great. I went to pick up the car that night and just as they drove the car out of the garage it ran out of fuel. They put some fuel in for me and I drove it home.

On the way home the check engine light came on(C.E.L). I took it back and they said it was on o2 sensor thay reset it but it came back on. They have now replaced all o2 sensors twice!! and still the light comes on. I have replaced the spark plugs, air filter, checked the fuel pump and filter, and replaced the air flow meter myself. ran umpteen fuel treatment through the car and still the light comes on and now it has a little hiccup and hesitates now and then. The light will come on wihout fail within 10-30 miles.

Toyota said on my last visit, that it could be a loose or corroded connection within the cars wiring harness but they could not be sure.

Please help this has been going on for over a year!!!

Any suggestions??

Alan

Car Toyota Yaris 1.3 CDX 2000 W reg

[armoredfist2002]

Surely if it's bringing up a cel, it should also be bringing up a code.

Just a thought, check the cat

[alan.motherwell]

Surely if it's bringing up a cel, it should also be bringing up a code.

Just a thought, check the cat

Yes the code is for the o2 sensor it was the heater circuit can't rember which bank or sensor but it's the one after the cat. P0135 if remeber correctly was the code, but all sensors have been replaced twice with no effect so that rules them out. How can I check the CAT short of replacing it.

[armoredfist2002]

emissions check, at an MOT station.

If the cat's on it's way out you may get the check engine light because of the higher emissions.

Other than that i'm not sure, as you've done the most common first thing to do.

check this link out, it has all the codes, but no P codes at the moment, but you may find something.

http://www.toyotaownersclub.com/forum/viewtopic.php?t=1353

[alan.motherwell]

emissions check, at an MOT station.

If the cat's on it's way out you may get the check engine light because of the higher emissions.

Other than that i'm not sure, as you've done the most common first thing to do.

check this link out, it has all the codes, but no P codes at the moment, but you may find something.

http://www.toyotaownersclub.com/forum/viewtopic.php?t=1353

Nope had CAT checked, all OK.

What about a bad wiring harness, or coil?? I'm running low on options.

When I disconect the o2 sensor after the CAT it runs great!! Plug it back in and it hop, skips and jumps!!

Anyone got any ideas

[alan.motherwell]

emissions check, at an MOT station.

If the cat's on it's way out you may get the check engine light because of the higher emissions.

Other than that i'm not sure, as you've done the most common first thing to do.

check this link out, it has all the codes, but no P codes at the moment, but you may find something.

http://www.toyotaownersclub.com/forum/viewtopic.php?t=1353

Nope had CAT checked, all OK.

What about a bad wiring harness, or coil?? I'm running low on options.

When I disconect the o2 sensor after the CAT it runs great!! Plug it back in and it hop, skips and jumps!!

Anyone got any ideas

Just an update the code is P0141 O2 Heater Circuit

[Starensis]

Just a thought..........

Did they fit OEM sensors or after market? If after market, check the sensing circuit is not x-wired with heating circuit.

I have changed mine with after market & had to swap wires in connector to obtain correct configuration, otherwise light will come on.

[petrolhead]

sound like faulty ecu to me

[alan.motherwell]

Just a thought..........

Did they fit OEM sensors or after market? If after market, check the sensing circuit is not x-wired with heating circuit.

I have changed mine with after market & had to swap wires in connector to obtain correct configuration, otherwise light will come on.

No they are both brand new genuine toyota sensor fitted by toyota. Now my car is running great, still get the p0141 code after 10-30 miles or so. What about the egr/Vacum switching valve?

[alan.motherwell]

Just a thought..........

Did they fit OEM sensors or after market? If after market, check the sensing circuit is not x-wired with heating circuit.

I have changed mine with after market & had to swap wires in connector to obtain correct configuration, otherwise light will come on.

No they are both brand new genuine toyota sensor fitted by toyota. Now my car is running great, still get the p0141 code after 10-30 miles or so. What about the egr/Vacum switching valve?

[Slr]

Hello to everyone, I am new to this forum, but long time reading.

I have seen this fault in a couple of 2002 rallye cup Yaris I tune here and I spent long time looking for the cause of this lambda heater circuit code and finally I found that the fault code is not right at the list.

The first thing I have done was to change the lambda sensors first and second ones, check the wiring harness looking for damage by heat or cutting, everything right. Drove the car and at a couple of miles the same fault code again back, then I have done a real time datalogging and the cause of the fault was the "dash board", I had another one in the garage and do the test, surprised because the fault code didn't came up again. I try to understand the way the ECU sees this fault and looking at the wiring, the Speed sensor signal goes to the dash and then goes to the ECU that "see" the speed and decide if you are accelerating or not, if this signal is not the way it should be the you've got a MIL light going on and the mistaken fault code.

May be this experience can help you... or not. ;)

Sorry for my poor english, didn't went to study english, always stop at the garage :D .

[alan.motherwell]

Hello to everyone, I am new to this forum, but long time reading.

I have seen this fault in a couple of 2002 rallye cup Yaris I tune here and I spent long time looking for the cause of this lambda heater circuit code and finally I found that the fault code is not right at the list.

The first thing I have done was to change the lambda sensors first and second ones, check the wiring harness looking for damage by heat or cutting, everything right. Drove the car and at a couple of miles the same fault code again back, then I have done a real time datalogging and the cause of the fault was the "dash board", I had another one in the garage and do the test, surprised because the fault code didn't came up again. I try to understand the way the ECU sees this fault and looking at the wiring, the Speed sensor signal goes to the dash and then goes to the ECU that "see" the speed and decide if you are accelerating or not, if this signal is not the way it should be the you've got a MIL light going on and the mistaken fault code.

May be this experience can help you... or not. ;)

Sorry for my poor english, didn't went to study english, always stop at the garage :D .

Hmmm I'll check that as I recently fitted a TNS 200 which is spliced into the speed sensor wire. Let you know how it goes.

Al

[Starensis]

Code definition is :- Oxygen sensor 2, bank 1. Heating circuit.

Usually picks this code up when Engine ECU does not detect correct resistance through sensor heating circuit.

The heating circuit warms up the sensor so it reaches operating temperature quickly, however, you will not detect any performance loss.

Check connections at sensor & ECU, plus terminals inside connectors are not corroded.

[Benno_uk]

Err just a thought. You do know these sensors are colour coded? Have they fitted the correct one to the correct place?

[Starensis]

They are only usually coded for cable length, function of sensor is same.

[alan.motherwell]

Hello to everyone, I am new to this forum, but long time reading.

I have seen this fault in a couple of 2002 rallye cup Yaris I tune here and I spent long time looking for the cause of this lambda heater circuit code and finally I found that the fault code is not right at the list.

The first thing I have done was to change the lambda sensors first and second ones, check the wiring harness looking for damage by heat or cutting, everything right. Drove the car and at a couple of miles the same fault code again back, then I have done a real time datalogging and the cause of the fault was the "dash board", I had another one in the garage and do the test, surprised because the fault code didn't came up again. I try to understand the way the ECU sees this fault and looking at the wiring, the Speed sensor signal goes to the dash and then goes to the ECU that "see" the speed and decide if you are accelerating or not, if this signal is not the way it should be the you've got a MIL light going on and the mistaken fault code.

May be this experience can help you... or not. ;)

Sorry for my poor english, didn't went to study english, always stop at the garage :D .

How do you know if this is the problem and how do you fix this?

[alan.motherwell]

Code definition is :- Oxygen sensor 2, bank 1. Heating circuit.

Usually picks this code up when Engine ECU does not detect correct resistance through sensor heating circuit.

The heating circuit warms up the sensor so it reaches operating temperature quickly, however, you will not detect any performance loss.

Check connections at sensor & ECU, plus terminals inside connectors are not corroded.

I've checked the O2 sensor connection which is the one after the CAT i believe, looks ok, what connectors and where on the ECU should I look. Is there a diagram which is easy to follow to trace the o2 harness inside the car.

[Slr]

I was lucky because I had the other rally yaris at the garage for new mods and ask to owner about swapping the cluster to the other to check if it solve the problem (erratic speed from ecu looking at datalogging compared with the racelogic performance box speed info). I use the performance box but a gps or another speed measurement tool will do the job.

I don´t understand way the ECU send the "Oxygen sensor 2, bank 1. Heating circuit" fault code when the cause is the speed signal not arriving or corrupted to ECU speed input, may be is a human mistake writing the fault code list.

This was my case, I can´t confirm it will be yours but you don´t miss anything because the main dealer have done everything and they can´t solve the problem. I have to say that here, some toyota models come from diferent factorys and there is comon faults for each series coming from each factory.

example: made in France 2004 corolla luna 1.4c.c vvti (gearbox shifting faults)

[alan.motherwell]

I was lucky because I had the other rally yaris at the garage for new mods and ask to owner about swapping the cluster to the other to check if it solve the problem (erratic speed from ecu looking at datalogging compared with the racelogic performance box speed info). I use the performance box but a gps or another speed measurement tool will do the job.

I don´t understand way the ECU send the "Oxygen sensor 2, bank 1. Heating circuit" fault code when the cause is the speed signal not arriving or corrupted to ECU speed input, may be is a human mistake writing the fault code list.

This was my case, I can´t confirm it will be yours but you don´t miss anything because the main dealer have done everything and they can´t solve the problem. I have to say that here, some toyota models come from diferent factorys and there is comon faults for each series coming from each factory.

example: made in France 2004 corolla luna 1.4c.c vvti (gearbox shifting faults)

Some other symptoms I forgot to mention, when cold the car will idle high then low, irratically only lasts a few seconds and only when cold. But recently the fuel tank would show empty on the digital display when starting up, and the tank is full. I turn the ignition off and on and it reads correct fuel amount, very strange. Any ideas anyone, it sounds like it could ba an ecu on the way out??

Alan

[Benno_uk]

They are only usually coded for cable length, function of sensor is same.

You rekon? :censor:

[alan.motherwell]

Problem solved took out bulb to engine warning light ta da!! Well I give in with this silly fault.

[Lewi.corolla tsport]

Has anybody found a solution to this I have the same problem with my 2002 t sport Corolla changed the lambada sensor genuine Toyota sensor and the correct one..... I’ve watched some videos one saying it most likely would be from 3 things.

1 bad e.c.t sensor

2 the earth connection maybe loose or is corroded causing bad connection( I was hoping someone could tell me where I can find this connection) 

3 faulty lambada 

I wouldn’t mind living with the engine management light on but on the t sport the vcs light comes on and the traction control switches off and won’t turn on 

[Perfection]

Had you measured the heater circuit resistance? 

 

[Madasafish]

On 2/20/2008 at 2:18 PM, alan.motherwell said:

Some other symptoms I forgot to mention, when cold the car will idle high then low, irratically only lasts a few seconds and only when cold. But recently the fuel tank would show empty on the digital display when starting up, and the tank is full. I turn the ignition off and on and it reads correct fuel amount, very strange. Any ideas anyone, it sounds like it could ba an ecu on the way out??

Alan

Sounds like the connections to the guage are corroded/dirty. - probably at the tank end. I believe (?guess) you can access from the rear - under rear seat. 

[Mike ayres]

Hi can somebody tell me where the plug fits into o2 rear oxygen sensor please