PO420.....so now what?

[la_scanner]

reading different things. but happy to say at least i have narrowed down problem of my previous posts on here.

[la_scanner]

???

[AlexNet0]

A code P0420 may mean that one or more of the following has happened:

• Leaded fuel was used where unleaded was called for
• An oxygen sensor is not reading (functioning) properly
• The engine coolant
  temperature sensor is not working properly
• Damaged or leaking exhaust manifold
  / catalytic converter / exhaust pipe
• Retarded spark timing
• The oxygen sensors in front and behind the converter are reporting too similar of readings

google ftw

Some suggested steps for troubleshooting a P0420 code include:

• Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required.
• Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady).
• Inspect the downstream heated oxygen sensor (HO2), replace if necessary
• Replace the catalytic converter

[Danish Yaris]

Hi

I would say it´s probably the oxygensensor when it says bank 1.

Regards Steven.

[Loren]

Now you Google the code and see what it means.

[eTiMaGo]

it can mean a lot of things indeed, but mostly that your catalytic converter is not working properly. Have you done any kinds of mods to your car?

You best bet is to take it to the dealer to check... Or you can just clear the code and hope it does not show up again..

[eTiMaGo]

and now re-reading your previous thread about putting diesel in the car, it's quite likely that the code is just a temporary one as the sensors didn't like the way the diesel fumes interacted with them. But, there's also a possibility that your catalytic converters are damaged, so taking it to the dealer is still the best bet.

[la_scanner]

Originally Posted by eTiMaGo

and now re-reading your previous thread about putting diesel in the car, it's quite likely that the code is just a temporary one as the sensors didn't like the way the diesel fumes interacted with them. But, there's also a possibility that your catalytic converters are damaged, so taking it to the dealer is still the best bet.

well fuel was put in over a month ago now or more actually. indicator light has been reset once by toyota and once by a mechanic in glendora,ca. the one that said oh okay yes its spark plugs and charges $138.00. thats what pushed me to buy this reader. even though i have seen worse in the past. did i miss anything? oh probably!

[eTiMaGo]

I'm sorry, I really don't think there's anything anyone here can do to help... If you don't wanna go see the dealer again (understandable), reset the code and cross your fingers it does not show up again...

[la_scanner]

Originally Posted by eTiMaGo

I'm sorry, I really don't think there's anything anyone here can do to help... If you don't wanna go see the dealer again (understandable), reset the code and cross your fingers it does not show up again...

well its not a matter of not wanting to go to dealership. i am curisous about this almost 1000 dollar estimate mt grandma got through toyota. from what i read it looks like there is a warranty for catalytic converter up to 80,000 miles. probably read wrong though.

[la_scanner]

Originally Posted by Loren

Now you Google the code and see what it means.

even with google, or software that i got. it still doesn't narrow it down as much as i would like.

[la_scanner]

Originally Posted by eTiMaGo

it can mean a lot of things indeed, but mostly that your catalytic converter is not working properly. Have you done any kinds of mods to your car?

You best bet is to take it to the dealer to check... Or you can just clear the code and hope it does not show up again..

no mods

basic and simple yaris here

[eTiMaGo]

something wrong with the catalytic converter, i don't see how it can be more detailed than that

If there is a warranty on it, and if they don't revoke it due to the diesel incident, then do it!

[la_scanner]

Originally Posted by eTiMaGo

something wrong with the catalytic converter, i don't see how it can be more detailed than that

If there is a warranty on it, and if they don't revoke it due to the diesel incident, then do it!

well but then again doesn't that code MAYBE mean that? what about the maybe spark timing? or maybe a hose not sealed or a plug not tight, etc.
the code p0420 from what i have looked up seems to be a common one and one with one too many possibilities. but of course. warranty = $0 at least the last time i checked. also correct me if im wrong but toyota did say wrong plugs are in, well not the brand they want are in. so that would hopefully make this a warrantable fix. no need to bring up deisel being put in over a month ago and what not.

Stored:
P0420 Catalyst System Efficiency Below Threshold (Bank 1)

Pending:
P0420 Catalyst System Efficiency Below Threshold (Bank 1)

MIL ON
MisFire Monitor Complete
Fuel System Monitor Complete
Comprehensive Component Monitor Complete
Catalyst Monitor Complete
Heated Catalyst Monitor Not Supported
Evaporative System Monitor Complete
Secondary Air System Monitor Not Supported
A/C System Refrigerant Monitor Not Supported
Oxygen Sensor Monitor Complete
Oxygen Sensor Heater Monitor Complete
EGR System Monitor Not Supported

DTC for which Freeze Frame was Stored P0420
Fuel System 1 Status Closed Loop
Fuel System 2 Status Not Supported
Calculated LOAD Value 77.25 %
Engine Coolant Temp 181.40 °F
Short Term Fuel Trim - Bank 1 5.47 %
Long Term Fuel Trim - Bank 1 -0.78 %
Engine RPM 2339 rpm
Vehicle Speed Sensor 54.68 mph
Ignition Timing Advance #1 Cylinder 25.00 °
Intake Air Temperature 69.80 °F
Air Flow Rate Mass Air Flow Sensor 2.57 lb/min
Absolute Throttle Position 28.24 %
Time Since Engine Start 1071 sec
Bank 1 - Sensor 1 Equivalence Ratio 1.06
Bank 1 - Sensor 1 O2S Voltage 3.44 V
Commanded Evaporative Purge 100.00 %
# Warm-ups since DTC Cleared 3
Distance since DTC Cleared 27.34 mi
Barometric Pressure 28.94 inHg
Bank 1 - Sensor 1 Equivalence Ratio 1.06
Bank 1 - Sensor 1 O2S Current 0.09 mA
Catalyst Temperature Bank 1 - Sensor 1 1274.90 °F
Catalyst Temperature Bank 1 - Sensor 2 1274.90 °F
Control Module Voltage 13.85 V
Absolute Load Value 56.08 %
Commanded Equivalence Ratio 0.97
Relative Throttle Position 10.98 %
Absolute Throttle Position B 62.75 %
Accelerator Pedal Position D 25.10 %
Accelerator Pedal Position E 41.18 %
Commanded Throttle Actuator 28.24 %
Time since DTC Cleared 0 hr 53 min

[eTiMaGo]

Here's as detailed as you can get:

P0420 Catalyst System Efficiency Below Threshold (Bank 1)

Causes:
- Front exhaust pipe (with Three-Way Catalytic Converter)
- Gas leakage from exhaust system
- A/F sensor (sensor 1)
- HO2 sensor (sensor 2)

If it was a timing error or plug not tight, you'd have a different code, that's the whole reason for being of these diagnostic codes, to help you pinpoint the problem, not maybe something else

Thanks for posting the stored freeze frame value, quite interesting! Only thing that I think is out of order: Bank 1 - Sensor 1 O2S Voltage 3.44 V

Looking at the repair manuals the normal range for this sensor should be usually less than 1V? So yes, in this case, it seems to narrow the problem down to the O2 sensor being defective. But don't take my word for it, I am not a qualified mechanic, just a geek who likes to look up and understand technical information

[la_scanner]

Originally Posted by eTiMaGo

Here's as detailed as you can get:

P0420 Catalyst System Efficiency Below Threshold (Bank 1)

Causes:
- Front exhaust pipe (with Three-Way Catalytic Converter)
- Gas leakage from exhaust system
- A/F sensor (sensor 1)
- HO2 sensor (sensor 2)

If it was a timing error or plug not tight, you'd have a different code, that's the whole reason for being of these diagnostic codes, to help you pinpoint the problem, not maybe something else

Thanks for posting the stored freeze frame value, quite interesting! Only thing that I think is out of order: Bank 1 - Sensor 1 O2S Voltage 3.44 V

Looking at the repair manuals the normal range for this sensor should be usually less than 1V? So yes, in this case, it seems to narrow the problem down to the O2 sensor being defective. But don't take my word for it, I am not a qualified mechanic, just a geek who likes to look up and understand technical information

I totally respect that about you. thanks for your input. i do have to ask though... does this mean o2 sensor is problem(maybe) in lieu of expensive catalytic converter. too many questions. i know, i know.

keep in mind that i have not read manual on this code reader so i only had about 2 minutes earlier yesterday to plug in and see if anything would happen. im wondering when i try it out today. is there more i can do while using the reader to get more info. or is it really as simple as plug in. wait, unplug and view on pc? im not even sure how i did that freeze frame thing. time to look into that. thanks geek

[eTiMaGo]

well the way I see it, either something wrong with the cat is causing the (perfectly fine) sensor to read out of range, or the sensor itself is faulty. Without a Toyota technician's actual computer tester unit ($2000+ on eBay), there's no way to know without physical inspection.

[la_scanner]

appreciate it!