Hi All,

A month ago, at about 109K miles, I got my first Check Engine light with a PO 420 code (Catalytic Converter) in my 1999 TL. After some research, I chemically decarbonized the engine that also results in overheating the Cat. After resetting the light and waiting for the EU to fully cycle, the light was off. Today the Check Engine light reappeared. My plan is to first change the front Oxygen sensor and, if necessary, then change the Cat.

I would like your thoughts on my plan as well as some recommendations on which aftermarket brand of front O2 sensor and Cat to purchase. Although I have always purchased parts from Acura directly, due to the high cost of these parts, I am not looking to purchase the cheapest aftermarket parts but those that the listers has had the most success with.

Thanks and all the best,
Ray (RAC68)

 

Are you in the usa?
what did you use to clean the engine inside?
many times that will result in crud on the O2 which self clears in a few days of driving

have a muffler shop test the cat for you- they ck flow rate and temp to see if its clogged or fallen apart inside
Does it rev the same as always or slower or faster than normal?
rpm hits a sluggish point at 5000? wont rev beyond that- when driving
(there is a 5k rev limiter in park or n on the car)

the O2 sensor can be tested with a multimeter for function
Denso is the OE brand and best aftermarket replacement

cats- see our sponsored sales area for vendor Excelerate, he has cats from street cheap to full performance, for better prices than a shop will quote you

a lot of times you simply need to clean the EGR ports thru the intake manifold-
its remove manifold and clean by hand- no spray cleaner will do the job
Thats needed about every 75kmiles, per our moderator with 350 kmiles on his TL

 

most parts stores will ck the codes for free- if you have a ck engine light there is a code- it may have changed from first testing

reset ecu by pulling the clock fuse on passenger end of dash

 

Hi 01tl4tl,

Thanks for your response as your guidance is much appreciated.

To answer your first question, yes, I live in Central NJ.

On your second, I am not sure the name of the decarbonizing kit but a mechanic friend recommended I take a shot and $30 kit sold at AutoZone. The kit included a spray to be directed into the throttle body, a liquid fed through a vacuum port, and a liquid poured into the gas tank. I reset the EU after the application and initially ran the car for about 25 miles for the EU to run all tests and found the code had cleared. For the next month (more than 200 miles or so), no light…then a few days ago the light came back.

Per your suggestion, I have called a few muffler shops for a cat flow test but, as yet, have not found one willing to do it. Is this a rather expensive or difficult test or maybe I am using the wrong language?

The car seems to run as usual with no perceptible deterioration in acceleration or other performance qualities. Acura cleaned the EGR about 40K miles (3-years) ago and I hope it doesn’t build up carbon that fast. The only other issue present is the replacement of motor mounts scheduled for the spring when warm enough to do the job.

As you can see, though I really like and intend to keep this car, I do not rack up much mileage.

From your recommendation, I note that Excelerate carries Magniflow cats. As I have always purchased my parts directly from Acura, I am depending on the experiences of others to verify that an aftermarket part like Magniflow would perform as well?

Tomorrow, I will be going back to AutoZone to check the code. If it is the 0420 again, what sequence of replacements do your recommend (front O2, Cat, rear O2, other) to keep the cost down as well as reduce the work (I will be doing). It’s cold in NJ and I will be working in an unheated garage to deal with a March DMV Inspection date.

Thanks again and sorry for the delay in responding.
All the best,

 

did you use the master vac port at the TB--with the hose clamp and metal nipple?
had to remove the plastic engine cover for access to that and to remove the snout to air filter - so you could spray the TB plate,,correct?

I would repeat with seafoam in gas and master vac port
have no idea what kit you got

dont buy parts without testing for failure!!- o2 SENSOR has a specified range with multimeter
a $3 tool can save you 90 bucks
If you insist on buying parts at random,, start at the front O2,

magnaflow is highly respected company for stock and full on race car parts-
exhaust specialist

 

it takes more than a few miles for the ecu to run all its test and reprogram its running specs, a few weeks-couple hundred miles

with seafoam or any cleaner- do the blow out drive to get rid of crud before thinking about a reset- and its not normally needed to reset ecu
making the car learn while puking out gunk?! not the best plan~

 

I dont know about NJ muffler shops
what are you asking them? Can I come in for FREE testing?

call and ask if they can test to see if yours is bad, how do they test cats to see if they need replacement

so 40k ago acura did the 99s only recall on egr port and installed a sleeve in it
Still plugs up every 75kmiles or less and needs cleaning, that single port takes all the crud
6cyl 6 port go 75, so you may be less

 

bad front or rear motor mounts will cause a mystery vacuum leak
as they are boosted off a main vac line,,,