OBD. scanner question

[flembo]

The check engine light came on on my 2004 toyota Tundra. The code says PO 420 Catalyst Efficiency below threshold (bank 1). Is that the catalytic converter.It runs fine.Is a catalytic converter the same as a catalyst.

 

[RayP(MI)]

I would take that to say the catalytic converter not working at peak or perhaps good efficiency. Guessing you are in for a new converter.

 

[Phil9N3667]

A co-worker recently had the same DTC on his Nissan pickup and it was the O2 sensor on the converter. When he got done R&R the sensor, I cleared the DTC with my scan tool and he said last week that the light hadn"t come back on yet. I would find a reputable tech that you could trust and get him to verify it for you. Also, you could go to OBD-CODES.com and see what they tell you. This is a site that forums/reports like we do here. Good luck.

 

[glennster]

heres some information for you on the po 420 code

The catalytic converter has an oxygen sensor in front and behind it. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensor waveform reading should fluctuate. The downstream O2 sensor reading should be fairly steady. Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar. This is indicative of (among other things) a converter that is not working as efficiently as it should be (according to specs). It is part of the vehicle emissions system.

causes

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
possible soloutions

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
One thing to note is that many vehicle manufacturers offer a longer warranty on emissions-related parts. So if you have a newer car but it"s out of it"s bumper-to-bumper warranty, there still may be warranty on this type of problem. Many manufacturers give a five year, unlimited mileage warranty on these items. It"s worth checking into.

 

[Malibu Nick]

Your Tundra has several o2 sensors. Upstream of the cat will be a sensor to monitor your fuel mixture for rich/lean conditions. Downstream of each cat you will find an o2 sensor to monitor the level of oxygen left in the exhaust mixture. The difference between measurements up and down stream is used to determine if your cat is working properly. An easy way to test if your cat is in fact working is to take a temperature reading before and after the cat. A properly working catalytic converter will be slightly warmer behind than in front. Most of the cars and trucks I see with that code have problems with the wiring to the o2 sensor itself, a bad o2 sensor, or an exhaust leak causing fluctuations in the readings. Sorry for the long post. I was happy to be able to help rather than asking the questions for one time on this tractor forum.

 

[flembo]

Thanks for all replies. Glennster without a doubt you know what your talking about.It sounds like it could be a number of things so I guesse I won't just throw a converter at it, this truck is going in for a recall frame change shortly so maybe I will have them handle it at the same time. Again Thanks all

 

[John in MD]

Any time you don't know what the code means just go to Google and enter it in Google search.

 

[Bryan inIowa]

Remember codes are usually "Cause and effect "

 

[Sprint 6]

Oxygen sensors will not cause a P0420, they have to pass their monitor before the P0420 monitor can run. Top things that cause a converter failure is oil usage or running rich due to skewed MAF sensor.