p0420 Some assistance please

Hi All,

I read through the forums this morning, Thanks for the advice about Autozone being able to read the codes. Last night while on the highway traveling home the engine light came on. I immediately pulled over and confirmed engine oil level was within range on stick, looked for coolant leaks & checked transmission fluid was up. We have a 2003 Camry XLE V6. Since no immediate threat could be found we drove another 60 miles home.

Autozone found the code to be PO420. The 4 possible causes are converter defective, misfire, vacuum leak & engine leaking into exhaust.

I've read the posts and seen your suggestions and will probably go to the dealer to have the converter looked at. I have 60,000 miles on the car.
An efficiency test was just done on the car ( req'd in canada every 2 years).
The test was done twice once at idle and another at 1742 rpm.
At idle the HC ppm read 4 (limit 150) & co% reading was 0.00 (limit 0.70), NO ppm was n/a for this test.
At 1742 RPM HC ppm read 4(limit 58) & co% read 0.00 (limit 0.32) & NO ppm read 1 (limit 435) Dilution was 15.0.

Gas cap pressure test passed.

I am pretty handy when it comes to repairs of electrical or mechanical nature. What I am having a hard time wrapping my head around is that the car just passed this test 3 weeks ago and now this problem occurs. If the convertor takes time to fail would the readings from the test not provide some evidence of this?

Thanks for your time & help.

Budz

Bring it to the dealer and have them check it. There are more than 4 reasons that could cause it. I don't know where you got the information about those 4 reasons you listed, but they're not accurate at all given the DTC listed.

The dealer can monitor the convertors and oxygen sensors to see what's going on. Three weeks ago you check engine light wasn't on so there wasn't a problem at that time.

I'll agree.... typically P04xx codes are predominantly related to evaporative emissions... so the Fuel cap was a good place to start. If it was loose (even a bit) and you tightened it after checking it, the light should go out, but only after a couple decent drives (15+ miles, if I remember right). The system uses 2-trip logic to make sure that it doesn't turn off the light prematurely.... I would definitely have the dealer check it, as it could be related to either the catalytic converter, the oxygen sensor(s) or other hard emissions components. Hopefully it's something covered... and if not, remind them (politely) about the business you just did with them and will likely continue to do with them... HTH

I'll agree.... typically P04xx codes are predominantly related to evaporative emissions... so the Fuel cap was a good place to start. If it was loose (even a bit) and you tightened it after checking it, the light should go out, but only after a couple decent drives (15+ miles, if I remember right). The system uses 2-trip logic to make sure that it doesn't turn off the light prematurely.... I would definitely have the dealer check it, as it could be related to either the catalytic converter, the oxygen sensor(s) or other hard emissions components. Hopefully it's something covered... and if not, remind them (politely) about the business you just did with them and will likely continue to do with them... HTH

DTC P0420 has nothing to do with the evaporative emissions system and the fuel cap was a meaningless place to start...



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 (http://www.obd-codes.com/p0420#)
Retarded spark timing
The oxygen sensors in front and behind the converter are reporting too similar of readings

http://www.obd-codes.com/p0420

DTC P0420 CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD (BANK 1)

CIRCUIT DESCRIPTION

http://library.motoralldata.com/alldata/MTRLIB~C38046~R0~OB0~P4R0H~N/0/89012112/92870401/98671763/98675772/34853741/34857029/34857030/34857663/122915129/103688830/120181541/113658062/104436983
DTC Detecting Conditionhttp://library.motoralldata.com/alldata/MTRLIB~C38046~R0~OB0~P4R0H~N/0/89012112/92870401/98671763/98675772/34853741/34857029/34857030/34857663/122915129/103688830/120181541/113658062/104436984
The ECM (http://library.motoralldata.com/alldata/MTRLIB~C38046~R0~OD~N/0/89012112/92870401/98671763/98675772/34853741/34857029/34857030/34857300) observes the waveform of the oxygen sensor (http://library.motoralldata.com/alldata/MTRLIB~C38046~R0~OD~N/0/89012112/92870401/98671763/98675772/34853741/34857029/34857030/34857572) located behind the catalyst to determine whether the catalyst performance has deteriorated.

If the catalyst is functioning normally, the waveform of the oxygen sensor (http://library.motoralldata.com/alldata/MTRLIB~C38046~R0~OD~N/0/89012112/92870401/98671763/98675772/34853741/34857029/34857030/34857572) located behind the catalyst switches back and forth between rich and lean much more slowly.

When the waveform of the oxygen sensor (http://library.motoralldata.com/alldata/MTRLIB~C38046~R0~OD~N/0/89012112/92870401/98671763/98675772/34853741/34857029/34857030/34857572) located behind the catalyst alternates flatteringly between rich and lean, it indicates that catalyst performance has deteriorated.

CONFIRMATION ENGINE RACING PATTERN

Confirmation Engine Racing Patternhttp://library.motoralldata.com/alldata/MTRLIB~C38046~R0~OB0~P4R0H~N/0/89012112/92870401/98671763/98675772/34853741/34857029/34857030/34857663/122915129/103688830/120181541/113658062/104436985


Connect the OBD II scan tool or the hand-held tester to the DLC (http://library.motoralldata.com/alldata/MTRLIB~C38046~R0~OD~N/0/89012112/92870401/98671763/98675772/34853741/34857029/34857030/34857209)3.
Start engine and warm it up with all the accessories switched OFF until the water temperature is stable.
Race the engine at 2,500 - 3,000 rpm for about 3 min .
When racing the engine at 3,000 rpm for 2 sec . and 2,000 rpm for 2 sec . alternately, check the waveform of the oxygen sensor (http://library.motoralldata.com/alldata/MTRLIB~C38046~R0~OD~N/0/89012112/92870401/98671763/98675772/34853741/34857029/34857030/34857572) (bank 1 sensor 2).Step 1 - 2http://library.motoralldata.com/alldata/MTRLIB~C38046~R0~OB0~P4R0H~N/0/89012112/92870401/98671763/98675772/34853741/34857029/34857030/34857663/122915129/103688830/120181541/113658062/104436986
Step 3 - 4http://library.motoralldata.com/alldata/MTRLIB~C38046~R0~OB0~P4R0H~N/0/89012112/92870401/98671763/98675772/34853741/34857029/34857030/34857663/122915129/103688830/120181541/113658062/104436987
INSPECTION PROCEDURE

HINT: Read freeze frame data using the hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.

Typically a P0420 is a Cat convertor needing replacement, Other than that there are some times when it needs a PCM Reprogram because the original program was to tight. Usually if an O2 sensor goes out it will set a different code. As long as the O2 sensors are not lazy or the program is fine your car will need a cat. I am not sure what the emmissions laws are in Canada but cats are covered for 80k in the states

DTC P0420 has nothing to do with the evaporative emissions system and the fuel cap was a meaningless place to start...




http://www.obd-codes.com/p0420


Forgive me... I was thinking P044x code... You are absolutely correct... :sosad: But I will still stand by the statement that in an instance like that, the best thing to do is have the dealer look at it... you certainly don't want the autozoner trying to diag the vehicle

Typically a P0420 is a Cat convertor needing replacement, Other than that there are some times when it needs a PCM Reprogram because the original program was to tight. Usually if an O2 sensor goes out it will set a different code. As long as the O2 sensors are not lazy or the program is fine your car will need a cat. I am not sure what the emmissions laws are in Canada but cats are covered for 80k in the states

I have this same code on my 02 Camry /w 181,000 miles. I think its the cat. The code came on about 2 months ago. How long until I absolutely have to replace it, and roughly how much will the dealer charge me to do it?

Forgive me... I was thinking P044x code... You are absolutely correct... :sosad: But I will still stand by the statement that in an instance like that, the best thing to do is have the dealer look at it... you certainly don't want the autozoner trying to diag the vehicle

they want us to diag there car since they dont have to shell out 80+ bucks at the dealer or any shop.

they want us to diag there car since they dont have to shell out 80+ bucks at the dealer or any shop.

This is true, but most shops will waive diag if the work is done... I don't knock it... it's a valuable selling tool :rockon:

::edit:: referring to the selling tool comment, I was referring to autozone offering OBDII scanning, not the techstream functionality... techstream is above & beyond the 69.95 generic OBD reader... and a whole lot better than the old scantools :)

p0420 is an evaporative emissions code, usually dealing with the catalyst.
the dealer has a techstream system which can be attached to the diag port on your camry and realtime read all of the issues with the car and said code and pinpoint the issue...sure it costs more, but its a very helpful tool i use every day at my dealer.

p0420 is an evaporative emissions code, usually dealing with the catalyst.
the dealer has a techstream system which can be attached to the diag port on your camry and realtime read all of the issues with the car and said code and pinpoint the issue...sure it costs more, but its a very helpful tool i use every day at my dealer.

Actually, it doesn't have anything to do with the Evap (fuel vapor recovery) system...

The dealership does have the very best tools for an easier and more accurate diagnosis.

Actually, it doesn't have anything to do with the Evap (fuel vapor recovery) system...

The dealership does have the very best tools for an easier and more accurate diagnosis.

Dont forget the chill factor. Could be temp related