ECM code PO420

Reply

  #1  
Old 09-18-10, 11:25 AM
Member
Thread Starter
Join Date: Oct 2005
Location: Lennox, CA.
Posts: 53
ECM code PO420

Hello, I have a 1996 Toyota Camry 4 cyl. I scanned my ECM and got the dreaded 420 code (catalytic converter efficiency running below threshold) aside if replacing converter could the trouble be in one of the two oxygen sensors above and below the converter, if so how could I check this. Thank you
 
Sponsored Links
  #2  
Old 09-18-10, 01:40 PM
ASE MASTER's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Aug 2010
Location: USA
Posts: 560
There are a number of possibilities for the setting of PO420 in any Toyota vehicle. Rather than waste time, and money (by just throwing changing parts at the problem till it’s fixed), clear the code, and drive with car with a “Tech II” scan tool hooked up. When the code sets again post the “Live Data”. also post the "Switching Rates" of the upstream and downstream O2 sensors.
 
  #3  
Old 09-18-10, 02:15 PM
mickblock's Avatar
Member
Join Date: Feb 2009
Location: Calumet Township, Indiana
Posts: 616
You don't say if this was the result of an engine light being on.
You just say you scanned your ecu.
ASE, if he has a mature CEL code then doesn't he already have the freeze frame data attached to it?
Does that data usually contain cross count data or is the Tech II scanner the only way to obtain that info? Cause that seems like the key
 
  #4  
Old 09-18-10, 04:01 PM
Unclediezel's Avatar
Member
Join Date: Dec 2006
Location: Northeastern PA.
Posts: 2,230
I just went thru this scenario this past week with a V6 chrysler Sebring. Stumped Me, Stumped The Other techs in the shop, Stumped the guys on the Tech Line....So here goes...

Vehicle comes in with CE lamp lit, PO420 stored... Freeze frame shows "IDENTICAL" voltages Both upstream and downstream..And VERY CLOSE "Cross Counts"...OK ....Cat is Junk..... If both sensors are reading The same, It means "Technically ," the cat Is Not CATALYZING...In essence..Its just a hollow Tube.
Replaced the cat , and all is well.....UNTIL...300 miles later, the vehicle is back, PO420 stored, and NOW..P0038, 1/2 O2 sensor ckt High....ACTIVE

REplace Downstream O2, High Ckt is fixed, but Po420 is still PENDING, and Sensors still Read Identical...Tech Line says CAt is Defective....Replace Converter Again.... All is well, ...until....1200 miles later, Vehicle returns, p0420 stored,.....

Now....The fix.....A loose Ground strap at the Passenger Strut tower..... Every Diagram I have looked at, shows NO RELATIONSHIP between That strap and Exhaust or Sensors....And Why is downstream Reading Identical to Upstream If it isnt Grounded????.... Truthfully....I dont know.....But the car Is fixed...

So..Before throwing parts at it, This is one of those cases , where There is no substitute for a PRO. TAke it somewhere and let them work their MAgic....and Have some piece of mind that Part of what you paid for is someone to stand behind their Diagnosis and Their Work.......
This Sebring Ate my lunch on 3 seperate occassions, But the customer was reimbursed for the Cat that was replaced unnecessarily, as well as the original Diag Time..
 
  #5  
Old 09-18-10, 04:01 PM
Member
Join Date: Oct 2008
Posts: 1,312
I have read that the oxygen sensors should be replaced every 30,000 to 60,000 miles as a regular maintenance item.

So if these have not been replaced in that long, I would replace them "just because". Be sure to get and apply anti-seize compound to the threads. Sometimes this comes with the oxygen sensor. This makes it easier to remove the oxygen sensor when it is time to replace it again.

Also these can be stuck in there very tight. Get a big long wrench and they have special sockets for these to allow the wire to hang out.

When you replace these, you will get better gas mileage, so they pay for themselves.
 

Last edited by Bill190; 09-18-10 at 04:38 PM.
  #6  
Old 09-18-10, 05:11 PM
Unclediezel's Avatar
Member
Join Date: Dec 2006
Location: Northeastern PA.
Posts: 2,230
Originally Posted by Bill190 View Post
I have read that the oxygen sensors should be replaced every 30,000 to 60,000 miles as a regular maintenance item.
When you replace these, you will get better gas mileage, so they pay for themselves.

Absolutely NOT.......

I have read the same from The sensor MFRs, But I know of no Auto Mfr that recommends Sensor replacement as part of a 30k or 60k service, Nor as a Scheduled Maintenance Item.

As Far as Fuel economy, Unless the sensor in the car is Blatantly defective, Replacing it with a "NEW" one will do absolutely Nothing. I do realize that they can "Degrade" oveer time, but enough degradation to actually affect fuel economy to a substantial savings, would be enough reason to deem it faulty.

A basic rule for Cars, Life, or any other situation you can Imagine.....You CANNOT make an Improvement unless what you have is INADEQUATE.
 
  #7  
Old 09-18-10, 05:52 PM
ASE MASTER's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Aug 2010
Location: USA
Posts: 560
amoreyou,

Don’t be to quick to throw the catalytic converter, or oxygen sensor’s under the bus. As with any system in a vehicle, and any code that is set, the basics have to be ruled out first.

PO420 Basics

Exhaust leaks.

Damaged exhaust pipes.

Damaged O2 sensor wiring (and or connectors).

Catalytic converter dents, holes, severe discoloration or rattle inside.

Plugged catalytic converter.

With a scan tool or oscilloscope, confirm a fairly steady waveform. A reading that fluctuates is a sign of an oxygen sensor issue.
 
  #8  
Old 09-18-10, 08:26 PM
Member
Join Date: Oct 2008
Posts: 1,312
Well then read what they have to say yourself...
(I'm just the messenger...)

This one says 30,000 to 50,000 miles...
Know When to Replace Your OEM Oxygen Sensor - O2 Sensor

This one says 30,000 to 100,000 miles...
OXYGEN SENSORS

Plenty more where that came from...
Google
 
  #9  
Old 09-18-10, 09:09 PM
Unclediezel's Avatar
Member
Join Date: Dec 2006
Location: Northeastern PA.
Posts: 2,230
C'mon now Bill........Those are all Parts Houses, Pitching to sell a product.....

I'm not going to pick at you personally, But everyone is so tightly wrapped in the "Maintenance" world, That nothing gets fixed anymore. Dont get me wrong, Scheduled Maintenance is a good thing, But not when it overshadows a Problem vehicle in neeed of repair.

Watch carefully....
Cooling System Service...149.95 as opposed to a new radiator at 400$ + 2.5 hrs of labor at 85 per hour... Round that off to 600 $

Now ...If you were a shop owner, which would you want to sell???? and why??

The system Service is Almost pure Profit unless the Tech is paid 100 bucks an hour (Actual Labor time is .5)

The radiator replacement is the cost of the part, and 2.5 hours at the techs hourly pay......
The shop owner actually made more moneyDoing the service, and has you thinking he did you a favor.....By saving you 600 bucks......Its a GAME...and everyone is playing it and getting rich.....Except the Good old Fashioned Competent Technician, Who is Going broke.

My favorite is the Transmission flush intended to fix the car That Slips going into second gear
 
  #10  
Old 09-18-10, 09:26 PM
ASE MASTER's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Aug 2010
Location: USA
Posts: 560
diezel,

(Quote) Pitching to sell a product

Why bother with a flush? Takes time and money. Try the "snake oil' below.

"BS" in a bottle. A bigger joke are the customer testimonials.


Lucas Transmission Fix : Lucas Oil - Lucas Transmission Fix
 
  #11  
Old 09-20-10, 06:16 AM
Member
Thread Starter
Join Date: Oct 2005
Location: Lennox, CA.
Posts: 53
PO420 ECM code

Thank you, everyone who offered a possible solution to what could have been a costly situation. I looked in depth all the info I received, one of the idea's was to check my coolant level. I found it very low, filled it then scanned for codes again. Warning lite was off and no codes showed up on my scanner. Big savings $$$ Thanks again everyone. Al
 
  #12  
Old 09-20-10, 07:59 AM
Member
Join Date: Aug 2006
Location: santa fe /texas
Posts: 998
Thumbs down

Originally Posted by Unclediezel View Post
C'mon now Bill........Those are all Parts Houses, Pitching to sell a product.....

I'm not going to pick at you personally, But everyone is so tightly wrapped in the "Maintenance" world, That nothing gets fixed anymore. Dont get me wrong, Scheduled Maintenance is a good thing, But not when it overshadows a Problem vehicle in neeed of repair.

Watch carefully....
Cooling System Service...149.95 as opposed to a new radiator at 400$ + 2.5 hrs of labor at 85 per hour... Round that off to 600 $

Now ...If you were a shop owner, which would you want to sell???? and why??

The system Service is Almost pure Profit unless the Tech is paid 100 bucks an hour (Actual Labor time is .5)

The radiator replacement is the cost of the part, and 2.5 hours at the techs hourly pay......
The shop owner actually made more moneyDoing the service, and has you thinking he did you a favor.....By saving you 600 bucks......Its a GAME...and everyone is playing it and getting rich.....Except the Good old Fashioned Competent Technician, Who is Going broke.
My favorite is the Transmission flush intended to fix the car That Slips going into second gear
UNCLE-our shop has even found a way to justify - cutting the tech's pay scale down to 75% of his regular hourly pay - for 'any' maintenance type work done!!
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'