Got the following via OBD-II scanner:

p0420 Catalyst System Efficiency Below Threshold (Bank 1)

1999 2.4L Caravan, 131,000 miles

Main question, do you think the catalytic converter has gone bad? Or should I have both upper and lower O2 sensors checked for proper voltage and functionality?

Check engine light came on for the first time since purchased new in 12/98. Has been sub freezing for the last couple of weeks but shouldn't affect efficiency of Cat huh?

The following was recommended from 2 dealerships:

1) Come in for diagnostic, will change what's necessary. Cost for diagnosis $120 will be taken off if you have done here. I then followed up with what the service writer has seen with this type of code error and he hesitated to give comments. Wherein I inquired regarding warrantee on work. He mentioned the 1 yr./12 month program but wouldn't guarantee the Check engine light would stay off as OTHER SYSTEMS MAY BE IN ERROR. Suspecting a pandora's box here, I hypotheticized replacement of uppersensor, and them resetting the computer only to have the light come on again after a few days of driving. The service writer then said, "It may require MORE work!" I followed up with,"Can't you diagnose and repair the situation the first time?" He then started with the canned talk, "We repair system problems as they come up, one at a time, and sometimes they may require multiple visits." This type of response just seemed like no answer to solving the problem. Didn't trust this dealership and will not seek their help.

2) Explained the code and mileage of vehicle to service writer. He came back with, "It's probably the catalytic converter, go to any reputable replacement shop and have a new one installed for less than you could here which will cost you $1,200. Make sure is is OBDII compliant. Drive car a few days and the light should go off. If not, take it here and we'll look at it then.

3) I also had two parts store mgr's suggest replacement of the upper sensor.

In conclusion, I'm leaning towards the CAT replacement as locally I can get it done for about the price of the sensor alone at under $100. My reasoning is, 131,000 miles is well beyond the 80,000 mile warrantee on the device and this logic was concurred with dealer 2.

Or am I off bases here? Any help would be appreciated at this point. I'm not driving the van as I want to my part to not excessively polute OUR air.

Tigger.....

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Just for the record, work done on vehicle other than wear and tear items.

A) Head Gasket 60,000miles.......new "multilayered" one installed Chrysler picked up cost after referring to TSB, Yeah!
B) New Rebuilt Chryler tranny 70,000miles....thank goodness for my mech/breakdown policy, only paid 250 deductible on the $2,750 job!
C) Fuel infection cleaner/service/tuneup/idle speed valve cleaned 102,000miles.....$393 out of pocket
D) Timing Belt/updated pulleys/timing covers/new water pump 110,000miles.....$795 out of pocket
E) Stabilizer bar bushings 119,000 miles.....did myself at $16.39
F) Right tie rod end replaced 123,000 miles......$59 out of pocket

 

Odds are that the cat is bad. Its ok to drive, the cat is still working, just not as well as it should. You can replace the oxygen sensors, but you will stil have the same problem. Tried it many times, always comes back. The problem with replacing the upstream sensor alone is that the PCM may really think that the cat is bad because you have one fresh sensor and one old. Basically what is happening is the PCM is comparing the upstream o2 signal to the downstream. Normally the upstream signal is fairly active, where the downstream is slow and calm. When the cat goes bad, the downstream looks similar to the upstream depending on how little the converter is doing. I would replace the cat and both of the o2 sensors. Also if you have the dealer install the 'V'line converter (similar to an aftermarket assembly, but cheaper than the original replacement), it has to have a minimum of around a 2 year warranty (federal law)

 

Brandon,

Thanks for your informative and comprehensive reply. I read many reports of 0420 episodes across differing platforms/makes/and models and was pretty much confused.

My dealer mentioned about $1,200 for a converter replacement. Any idea what the V line converter costs installed? Just a guestimate would be fine. And is the functionality adequate as I plan to keep this van for quite some time. Most all of my Mopars have driven over 200,000 miles before retiring.

Once again, your advice is appreciated.

Tiggerzz

 

Replacing it with the original equipment one should only cost at most $750, retail on the cats are $610 and $525 depending on whether you have CA emissions or not. The V-line will probably be around half of that which is a good price. And yes a cheapie will work as good as the original, they have to, federal law. They may not last as long but they will work good for a couple of years.