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Toyota Rav 4 2000 - Cat efficiency, code P0420 #

Posted by Allan Davis on December 13, 2011, 10:46 pm

Year of Manufacture *: 2000
Engine Size and Code *: 2.0 1AZ-FE
( Optional ) Scanner Used: Launch/Pico
( Optional) Fault Codes: P0420

Hi All
This car came to me for a MOT test via a trader. It passed but the engine light was on and i was asked to clear the codes. The codes related to o2 sensor heaters on 2 of the four sensors. The trader sold the car without repairing and when the light came back on the buyer had the sensors replaced by a local garage and the trader paid the bill. However now a catalyst efficiency code has appeared and i have been asked to have a look.I connected all four sensors to my pico and the B1S1 and B2S1 readings were both at 3.4v steady and B1S2 and B2S2 readings were switching between .2 and .8v regularly. I have gone onto the Toyota technical site and the spec. for the pre-cat sensors is as found. The problem is i would condemn the cat for the fact that the signals are switching after the cat but the emissions are perfect and i have not come across a 3.4v flat-line waveform from a four wire 02 sensor before.can anyone tell me if this is normal or do i have a fault or am i thick!
Thanks
Allan

Re: Toyota Rav 4 Cat efficiency

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on December 14, 2011, 12:32 am, in reply to "Toyota Rav 4 Cat efficiency"
Mark Carter

Hi Allan,

Your reading is normal for the sensor fitted to that vehicle, they are Toyota's early version of AFR sensors and not narrow band sensors as you where expecting.

It sounds like the cat is foo barred. The ECU will probably switch off the OBD monitoring with the heater faults being present, but now you have fixed them it has started doing its job again and the P0420 code is the result.

Check all the normal bits and bobs as far as cat efficiency faults go but you will probably need a new cat .

Regards Mark

Modern cars, Its all wizardry and witchcraft

Re: Toyota Rav 4 Cat efficiency

Posted by Allan Davis <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1846' width='330' height='300' border=0 style='border:none;'> on December 14, 2011, 7:13 am, in reply to "Re: Toyota Rav 4 Cat efficiency"

Hi Mark
Thanks for the reply. How would you test that type of sensor then?
If i connected the scope earth and signal to the signal and earth of the sensor would that work?
Thanks
Allan

Re: Toyota Rav 4 Cat efficiency

Posted by Sanjay Odedra <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3320' width='330' height='300' border=0 style='border:none;'> on December 14, 2011, 9:16 am, in reply to "Re: Toyota Rav 4 Cat efficiency"
Sanjay Odedra

Allan,save your self some trouble. This car needs an engine ecu re-flash at a toyota dealer. The software changes overun fuel cut off characteristics, the root cause of fault. Done 3 of these over a couple of years all still out there running fine.

Re: Toyota Rav 4 Cat efficiency

Posted by Peter Warman <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=Peter+Warman' width='330' height='300' border=0 style='border:none;'> on December 14, 2011, 1:53 pm, in reply to "Toyota Rav 4 Cat efficiency"
Peter Warman - Administrator

Hi Allan

There is some info in the archives

http://members5.boardhost.com/ukautotalk4/msg/1292330084.html

search "Toyota cat efficiency" on this forum

Peter

Re: Toyota Rav 4 Cat efficiency

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on December 15, 2011, 8:07 am, in reply to "Re: Toyota Rav 4 Cat efficiency"

Hi Sanjay,

>>> Allan,save your self some trouble. This car needs an engine ecu re-flash at a toyota dealer. The software changes overrun fuel cut off characteristics,<<<

Can you please explain to me how a ECU re-flash will repair the Cat?

The vehicle has been running for the best part of 12 years on the current software without the MIL being on and the ECU flagging P0420.

The re-flash you talk of is a alteration of the EOBD parameters monitoring and will not alter the fact that the OSC of the Cat has depleted, as shown by the post Cat sensor.

Regards Mark

Modern cars, Its all wizardry and witchcraft