I just had the CEL come on in my 99 TL and went to Autozone to have it checked, and the code said P0420 which is Catalyst Effiency Below Threshold (Bank 1). Lady said that it is probably the 02 sensor for that bank that could be defective. I have read other forums on here that said it could possibly be a bad catalyc converter. Anyone knows if it COULD indeed be more a 02 sensor problem or could it definitely be the catalyc converter. Also is there instructions on how to replace either one. Much help would be appreciated!!

Thanks guys,
y2k

 

I would start out by cleaning the EGR port and clearing the code to see if that solves it. If not its probably the O2

 

Yes fsttys, the thing is that I cleaned the EGR port out on the car at about 1 month ago because it too was throwing a code for insufficient flow or something to that affect cant quite remember, so I followed the instructions on here and took off the intake cover and found that the port was clogged severely. Anyways, that was about 1,000 miles ago and now Ive got this problem. So I think Im a step ahead of you there so do you think its really the O2 sensor or the catalytic converter itself? My friend has the same car and had the same problem and he stated he replaced the catalytic converter and NOT the 02 sensor and his light never appeared again.

 

P0420 i think ur car wants a BONG RIP ....lol...

 

 

hey y2 i have the same problem and they said it was the catalytic converter which is expensive,so i got to get that done

 

hey y2 i have the same problem and they said it was the catalytic converter which is expensive,so i got to get that done

 

Yeah Ill have to look into gettin mine fixed too. I mean it jus came on for the first time 2 days ago, and I had it reset and its still off for now. But I know that ugly CEL will rear its head again and Ill have to get it serviced. My Honda mechanic says it will cost about 5-7 hundred for the part alone and about 100 for the labor. But hey, at least its not the tranny Im still on the original and prays it stays that way.

 

If it is the cat contact excelerate for the RT performance cat. Its much much cheaper

 

Thanks fsttysm1 I'll check into it.

 

My car had the same code, and after cleaning the EGR port and driving for about 500 miles, it went way by itself. Been like 2000 miles now havent seen it.

Just a thought.

 

Cool thanks EnvyAce.........

 

no probs

 

I've got the same code in my 99. I had the 02's replaced and still have the code. I'm gonna have to check with Excelerate also.

 

I got the same code on my 99. Whats happens if u dont replace the cat?? I'm gonna try cleaning the egr first though.

 

so is the egr port the hole on the right side of the manifold. I keep hearing egr port cleaning so i looked it up and everyone is cleaning them but don't know where it is to clean it.

 

I have the same code on my GF TL but it sound like it might have a leak somewhere in the Exhaust system. I took it to a muffler shop but they did not notice any leaks. I am going to try to do the EGR cleaning and see if this help. fsttyms1 I remember in another thread about p0420 you mentioned using a scan tool that can monitor you o2 sensor. I have an Actron CP9180 and I did the o2 Monitor test. I got back some numbers and I am unsure of how exactly to read them. They are as follows:

O2 Bank 1 Sensor 1
TEST ID $30
MAX: 2.2(s)?
MEAS: 0.7(s)
MIN: 0.0
MOD: $0e

02 Bank 1 Sensor 2
TEST ID $45
MAX: 0.0800(v)?
MEAS: 0.800(v)
MIN: 0.290(v)
MOD: $0e

The link for the EGR cleaning as posted by fsttyms1 is http://www.in.honda.com/Rjanisis/pubs/SB/B00-004.PDF

 

There are different ways of testing the o2 sensor for the different cods. for the 420 you have to be driving.

Start the engine. hold the RPM at 3000 with no load (in park or neutral) until the radiator fan comes on.

Test drive at 40-55 mph for aprox 2 min, then decelerate for at least 3 seconds with teh throttle completely closed. Then reduce the vehicle speed to 35 mph and try to hold it until the scan tool indicates fail or pass as the TWC test result.

If the code fails then you need to look into the TWC (Three Way Catalytic converter)

 

Unfortunately I do not have access to a Honda Test Tool. I don't think the Actron has the TWC test. I think I will try the EGR cleaning and see what happens. Thanks for the help.

 

Here is the egr cleaning DIY- requires removal of intake manifold and cleaning the insides of it, and the egr port goes thru it
https://acurazine.com/forums/showthread.php?t=156252

 

double check that it doesnt. Alot that read live data will

 

After reading my manual for my Actron those are actually test ids that are specific to the vehicle. I tried googling it and came up with https://techinfo.honda.com/rjanisis/RJAAI001_mode.asp but the test IDS I had did not show up for a 1999 Acura TL. Does anyone have access to acura specific test IDs? I will check my test tool again to see if it has a Cat test.