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Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 - Fixed #

Posted by Peter Warman on November 5, 2009, 12:58 pm

Year of Manufacture *: 2002
Engine Code or CC *: 1ZZ - 1.8
( Optional ) Scanner Used: Modis 9.4

Hi All

Just wanted your thoughts on this one, before I go throwing a rear sensor at it

I have fault code P0141 on this vehicle, I have cleared it several times over the last few months but will come back at random, sometimes a month or two weeks

The MIL came back on yesterday and this is the Freeze Frame data

I have measures the resistance on front and rear sensors and I have 15 ohms on front and 16.9 ohms on rear, so the heater circuit of the rear sensor appears to be ok

I have done an emission test and have CO 0.0 and HC 10 with Lambda 1 so the cat appears to be working ok

The other thing is that the rear sensor appears to be switching

I would have thought the rear sensor signal should be a little flatter

So I am wondering now if its a random supply voltage problem to the rear sensor, or ECU fault

Any ideas as to how i can move forward on this

Many thanks

Peter

PS: Both front and rear heaters are supplied from fuse 19, front one has not logged a fault so I would imagine the rear sensor is getting power the same as the front

Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #

Posted by Ray Ferreday on November 5, 2009, 1:20 pm, in reply to "Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #"
Message modified by board administrator November 6, 2009, 3:04 pm

hi peter can you measure the amps at the fuse and disconnect each one and see what the difference is in the amps, by the way use a Toyota sensor. ray

Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #

Posted by Peter Warman on November 5, 2009, 2:14 pm, in reply to "Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #"
Peter Warman - Administrator

Hi Ray

Thanks for the reply

Just a bit more info having just done a bit more research

I had the vehicle hot and then disconnected both sensors, the rear one read 46 ohms, then checked 30 seconds later and it was 26 ohms, after a minute it was down to 16 ohms the same as the front one. I have found out that they flag a fault if the sensor resistance goes over 30 ohms?

I will have to check again Monday when he is back, I thought the higher reading was me being a bit ham fisted in a restricted space

Does this make any sense?

Peter

Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #

Posted by Glyn Morgan on November 5, 2009, 2:41 pm, in reply to "Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #"
Glyn Morgan

Hi Peter

Yes you are making some sense

As you know temperature can change resistance, the ecu usually monitor these circuits by current.

Honda often use different resistance heaters in their pre/post sensors, try your Multiscan it may have a pid for the sensor current.hth

Regards Glyn

Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #

Posted by Mark Carter on November 5, 2009, 9:38 pm, in reply to "Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #"
Mark Carter

Hi, Pete/Glyn
How are the both of you?
Pete the Ohms results that you posted make sense
Every thing at the moment(current posts) points to a O2 heater circuit malfunction and I agree with the earlier post of OE only.HTH

Regards Mark.

Modern cars, Its all wizardry and witchcraft

Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #

Posted by Tom Sinclair on November 5, 2009, 10:05 pm, in reply to "Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #"

Hi Peter, your code and other checks do indicate a sensor fault, however the waveforms posted suggest to me a catalyst fault. I have noticed that the downstream sensor picks up on cats sooner than an emissions test does. Also, if this is like some other Toyotas, with two stud HO2 sensor fixings, check studs and gaskets for air ingress. Cheers, Tom

Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #

Posted by Peter Warman on November 6, 2009, 6:21 am, in reply to "Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #"
Peter Warman - Administrator

Many thanks for the replies lads

He is going to bring the car back in Monday so I will re-check the heater resistance again when hot and do another cat test. I will also see what the Multiscan picks up for the o2 sensors

Peter

Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #

Posted by Ed Kaps on November 6, 2009, 8:52 am, in reply to "Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #"
Edward Kaps

Hi Peter
I would be wary of the 30 ohm max scenario, all these lambda heaters are PTC, i:e resistance increases as temp increases and it therefore follows that current will decrease.Bt the time you have disconnected it and measured it the resistance will already have started to decrease.
Load test the heater wires first and replace with OE sensor if no fault with wiring.
Ed Kaps

Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #

Posted by Dave McCall on November 7, 2009, 8:30 am, in reply to "Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #"
David C McCall

Hi Peter I can echo what a couple of the postings have said use a genuine o2 sensor. Several times we have picked up jobs where non genuine sensors have been used and have sometimes made the vehicle worse. Also check very carefully for dirty connections causing high resstance in the circuit I had an alfa last week with that problem. Dave Mccall

Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #

Posted by Dave Mccall on November 7, 2009, 8:39 am, in reply to "Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #"
David C McCall

Peter loooking at the switching voltage on the two sensors it looks as though the cat is a bit lazy or not lit up properly. I would expect to see the second sensor around 0.4 to 0.6 was the cat at operating temp ? Thinking aloud a constant rich mixture is going to cooler than a lean mixture so that heater element might be working harder and thus drawing more current ? just a thought Dave

Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #

Posted by Dave Hill on November 8, 2009, 8:11 pm, in reply to "Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #"

Hi Peter

Why not scope the heater circuits & evaluate what is happening in real time?

I think you have a low amps clamp with Modis. If so, then I recommend that you monitor the current flowing & also the voltage on each heater wire. If you start at key off & then key on, then start up. with 60 seconds on screen, you will see enough info to establish what is happening.

Here is a post I made a couple of years ago. although now I use an amps clamp to give further evidence, as to what is going on...........

Old post....

As with most electrical systems on a motor car, it is possible or even preferable to test with a scope.

It was whilst chatting to Dave Harney about O2 sensor heater circuits, that he mentioned his method of testing. I have tried it a few times & I must admit that it has been proved to be pretty conclusive for me.

It’s a simple test taking a few moments to set up, which involves the probing of both heater wires of the Lambda sensor. In my example I have also probed the signal wire so that I can assess the time taken for the sensor to become responsive.

I hope the animation does justice to the simplicity of the test.

Cheers all

Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #

Posted by Andrew West on November 9, 2009, 8:22 am, in reply to "Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #"
Andrew West

Hello all,
I have had quite a few Honda & Mitsubishi sensors with intermittent heater circuit faults & usually just change them with genuine units(usually denso which I can get from our local factors a lot cheaper than dealer).
I usually measure the current at the sensor, which confirms the supply & ecu ground at the same time if current is flowing, then I check supply & ground if no current flow. Quite often they are working when I check them & will do the same as yours, sometimes not bringing the light on for two weeks, so if a code comes up for heater circuit, I normally just change the respective sensor.
Regards, Andrew

Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #

Posted by Peter Warman on November 9, 2009, 5:52 pm, in reply to "Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #"
Peter Warman - Administrator

Many thanks for the additional posts

Had it back in this afternoon and the customer said the MIL came back on the next day

I checked the voltages sensor side similar to Daves waveform

Yellow = Front Sensor
Green - Rear Sensor

Engine Hot
Key Off
Key On....and battery voltage
Slight dip when starting
Full voltage present when running

I then checked with Amp Clamp (Pico)
0.5 amps at front sensor
0.0 amps at rear sensor

So check resistance again and this time
15 ohms at front
0 ohms at rear

So I think the sensor has now completely failed

New sensor on order from Toyota £158:00 plus vat

Thanks again for all the help, I certainly know more about 02 heater circuits now

Peter

Fixed #

Posted by Peter Warman on November 12, 2009, 10:01 am, in reply to "Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #"
Peter Warman - Administrator

Thanks for all the help lads

Replaced the sensor this morning, now have about .5 amps through both sensors

Peter

Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #

Posted by Dave Hill on January 10, 2010, 8:16 pm, in reply to "Re: Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #"

As an update on my test method. I now include a current trace, so that I can see the fuller picture!. I have seen a few examples where I have witnessed a complete circuit through the heater element, but when I looked at current flow I could see that there was an issue.

This is taken From a BMW E46 (straight 6) upstream sensor (this motor has two upstream & two downstream). This was the good sensor......

HTH

PS. Credit goes to Dave Harney for the test method. (Thanks Dave ✓ )

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