2002 S60 Check Engine Light Code P0420

[S602002]

We have a 2002 Volvo S60 base model. The check engine light (CEL) has been on for about one year now. It is throwing off a P0420 code. About one year ago, the first repair shop (we were out of state at the time) to look at the car cleaned out the throttle and replaced the fuel filter, then reset the CEL. It remained off for a few weeks, but then came back on. We have reset the light numerous times and it comes back on with the same code. We brought the car into a two different places since then and they both said the catalytic converter / manifold needs to be replaced. This is an expensive part and labor for it isn't cheap either. I'm not completely convinced its the converter/manifold from what I've read about symptoms of that problem. I don't want to prematurely replace a part of this cost. We used to use premium gas and switched to regular unleaded (87 octane) after the initial diagnosis about one year ago. The car runs excellent, there is no sluggishness, it gets great gas mileage on the highway (long haul trips we're getting in excess of 31mpg). There are no obvious cat converter related odors at least not regularly. On rare occasions we'll smell something but we've attributed that to outside odors (we live in a city with many sewer smells in certain areas). I've read numerous postings about 02 sensors being responsible for this CEL code. Can anyone tell me if one or more faulty O2 Sensors would throw off a P0420 code? Or if there is another probable cause for this CEL code? Thanks in advance for your help.

[swimNdrive]

This code is not unique to Volvo cars. Cat, O2 sensor or exhaust leak are the causes based on what I have read. You can goolge this code and get you some more information on Internet. There could be some other error codes more specific to your car or related to P0420 on your car. You may want to pull the code from VIDA or have a Volvo dealer to check it out.

[MoVolvos]

-

Purchased friend's 2002 CRV with 193K in Feb. The CEL with CAT Code would be on when he owned it for lengthy periods (8 months or more) and he was using Mobil 1 Synthetic and 87 Fuel. He put on about 80K in the last two years of Ownership of mostly freeway to and from work and had to put in half a quart every 1K miles.

Currently I am using a 5W-40 Dino with 91 Fuel. Only other things I've changed were the Air Filter and Spark Plugs. In October 1 week before Smog (was planning on selling) I had to start the car and move it several times on and off the drive way and the constant fresh fuel on a cold CAT triggered the CEL with P0420 for the first time since I owned it. Clear the codes and took it on several long drives and CEL has not come back. Try a different motor oil and run 91, put in fresh plugs if you have to and it may take care it.

I went to a very reputable Muffler shop and asked about a new CAT and it was about $1,500 for the part so he told me since it was not clogged just let it go as the Smog is good for 90 days for a Transfer of Ownership and is only needed every 2 years. Just getting old and not lighting up as it should he said but usable.

Fixing Bad Catalytic Converters With Inefficiency Code P0420


Scotty states that it does not take much for the Converter to put forth a code but it does not mean it is bad as was in my case also.


Blessings,

BKM

-

Pretty clean for a almost 200K Vehicle

Same motor oil after ~ 5K miles. Usually change it once a year

[chrism]

More info on diagnosing a bad cat:

[JDS60R]

Yes- bad oxygen sensors can cause the P0420 but if the car has over 150K on an 01/02 model year the cat is probably done. You have to fix the cat and what caused it.

It is a great idea to fix the probable causes first as "if" the cat is still ok it may pass.
Common causes of cat failure are:
Any other codes you have if engine related
Running for many miles with old fuel /air sensors or plugs so
Check plugs ( if more than 30K old - replace them )
Check compression -if low and/or exhaust is smoky it might be contaminating the cat
Check O2 sensors - The are only good for 100K miles - if older replace them
Check for leaking fuel injectors (when car is shut off and fuel injector and rail are pulled - do you see leaking fuel )
Check for exhaust manifold leaks
Tap converter near inlet and outlet with a soft hammer and listen for rattles
Run fuel injector cleaner ( many seem to like techron or Berrymans total fuel system cleaner)
Maf can be an issue but its rare.

We occasionally get one that will clean up but normally we get 01s and 02s with 150K miles and original O2 sensors and they have damaged the cat so we replace both O2 sensors($150) ( bosch direct fit bought through Matts link or FCP)spark plugs ($50)( Bosch - bought through FCP or Matts link) and I either weld in a Magnaflow cat($100) ( will need a 45 degree stainless pipe also for that model($65)) or I buy a catted downpipe online ($450)( ebay etc)

[S602002]

Thanks so much! The car has about 89,000 miles on it and the code has been on since the low to mid 70,000s. We've taken the car on some long trips and drove the miles up pretty quickly during the past year. The fuel filter and air filter were both replaced last year. Plugs aren't too old, but I'll check my records. I had read about the MAF and it does seem like a long shot.

I'll have to ask a mechanic to help out with this list of things to check.

Happy holidays!

[swimNdrive]

Do a PCV pressure test. It is easy. Search around you will find out how to do it.

[S602002]

Thanks for the reply swimNdrive. I'll check into this.

[IdahoBob]

Mine (230K miles) pops this code almost every time I drive somewhere with a 1500+' altitude change and then accelerate after stopping. Could be the sensor, the turbo is getting old. Still passed emissions, so I just carry the code checker every time we drive to Cheyenne, and re-set it. My concern with trying to replace the sensor is that there may not be enough sturdy metal in the body of the cat converter to hold up to the torque it would take to break the sensor free. Occasional code re-set vs. cat converter $.

Happy Motoring!