# 2005 toyota sienna - catalytic converter



## shirbon (Oct 2, 2014)

How many converters does a 2005 toyota sienna van have ?, more then 1, looks like it has 2 or 4, or is it some other part I see ? Thanks


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## Windows on Wash (Aug 30, 2011)

They will usually have 2 per bank, so 4 in this case.


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## shirbon (Oct 2, 2014)

So trouble code P0420 Catalyst System Efficiency Below Threshold ( Bank 1 ). I may have to replace 2 converters and possibly 4 ?


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## ron45 (Feb 25, 2014)

I would guess one.

Unless you have a true duel exhaust system then you would have two.


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## Windows on Wash (Aug 30, 2011)

If its the V6, you likely have 3 here. One on each banks as part of the manifold and it appears that there is one more after the mid (y-pipe).


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## Brainbucket (Mar 30, 2015)

P0420 is the bank 1 front converter. P0430 is bank 2 front converter. Just change the bank 1 front one and you'll be fine unless it dumped out into the rear one if it has a rear one. Didn't look it up.:vs_cool:


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## shirbon (Oct 2, 2014)

Yeah, I thought it had 4, but been a while since I worked on the exhaust ( when I did the Y pipe and probably o2 sensors ) maybe has 3 I have to look. Why does it need 3 or 4, isnt 1 enough ? which bank is bank 1, I can never remember, is it the bank in front closest to the bumper or the one in the rear closest to the fire wall ?, I'm thinking in front but I could be wrong. Thanks.


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## Brainbucket (Mar 30, 2015)

Recently we have been seeing many P0420 catalytic
converter efficiency codes. This code indicates the catalytic
converter is working minimally. However, there are a few things to
check before the catalytic converter is condemned!
The first step is to check the fuel trim readings. Monitor the fuel
trim readings at idle and at a part throttle cruise while driving at a
steady speed of approximately 50 to 55 miles per hour. The fuel
trim reading should remain close to zero percent. Plus or minus
10 percent is normal, but anything more than this should be
addressed before moving on to catalytic converter replacement.
The next step is to monitor the front oxygen sensor signal using
only a labscope. In most instances, scanner readings for oxygen
sensors update too slowly and a faulty sensor may not be noted.
Monitor the oxygen sensor both at idle for an extended period of
time and while test driving the vehicle at a steady cruise. The front
oxygen sensor should cross-count 8 to10 times in 10 seconds. If it
doesn’t, the sensor should be replaced.
A lazy oxygen sensor is the most common part failure to cause a
repeated code P0420 after the catalytic converter has already been
replaced. During the test drive, a front oxygen sensor can become
slow reacting and start to cross-count slowly, usually under slight
throttle opening and medium loads. When the front oxygen sensor
slows down, the catalytic converter does not work at maximum
efficiency and cools down. When this happens, the rear oxygen
sensor will start to cross-count more than normal and cause this
code to set.












If the front oxygen sensor has been replaced and the vehicle still






 
sets a P0420 code, the catalytic converter may be at fault and should 

be replaced if it cannot be brought back to working operation. 

Monitor the rear oxygen sensor at cruise to determine if it is crosscounting 

like the front one. This would confirm the converter is not 


working. It may be possible to revive the catalytic converter by 

heating up the converter. To do this, operate the vehicle until it 

reaches normal temperature. Ground one spark plug wire and run 

the vehicle for three minutes at 3000 rpm. This will cause the 

catalytic converter to run very hot, which can clean out the 

contamination and bring the converter back into operation. 

I know techs that have performed this procedure on their own 

vehicle and 9 months later, it was still working perfectly. Be aware, 


this may not work on all affected vehicles.:vs_cool:


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## shirbon (Oct 2, 2014)

So bank 1is in the back ?


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## Brainbucket (Mar 30, 2015)

shirbon said:


> So bank 1is in the back ?


 Yep:vs_cool:


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## shirbon (Oct 2, 2014)

Brainbucket, do you think maybe the cause could be a faulty oxygen sensor ? What is a labscope ?, nothing I have for sure. I havent looked at anything yet, I keep hoping its all a dream and I will wake up and its all fine - LOL. The sliding doors are faulty also.


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