Here is my dilema.

I keep getting the same codes popping up;
P0133 O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)
P0153 O2 Sensor Circuit Slow Response (Bank 2 Sensor 1)
P0420 Catalyst System Efficiency Below Threshold (Bank 1)
P0430 Catalyst System Efficiency Below Threshold (Bank 2)

Problem is that occasionally I have all four codes or, like now, just one code (P0420)
The codes clear themselves and sometimes I have no MIL illuminated. There doesn't appear to be a pattern.

O2 sensors renewed about six months ago.

I do not believe my cats have burnt out.

Any idea where to look or should I just replace the cats?

Thank you.

Mark

 

Ignore the P0420 & P0430 for now, as I think the PCM's ability to calculate those will be compromised by the other codes.

Why were your O2s replaced? Was it because you were already getting codes? Which ones? If the same as you now get then there's probably an underlying cause.

Were the new O2s definitely the correct types? This is vital. There are several different types.

Has the car been properly serviced including the correct oil grade and correct air filter, spark plugs, etc?

You can usually get a proper report from AE using its print button, btw.

 

You need cats, sorry,
buy a set of universals hi flo's like magnaflow for $100ea and have a competent muff shop weld them in. youll also need weld in 02 sensor bungs(4) as the factory are in the cats. The down streams can be welded in behind the cat, but close, upstream go right in the top. Misfires, poor responding 02's(youve had) that creat rich engine conditions and/or raw unburned fuel into cats. Will knock them out prematurely

 

The O2s giving the errors are upstream of the cats and recently new, so changing the cats won't affect them (or fix the codes) will it?

 

420 and 430 codes are cat codes

 

Thanks for your input guys.

Brutal, by welding up the O2 ports am I doing away with the sensors?

 

I know they're cat codes. But my questions remain unanswered.

 

I was getting the codes.

I had an air pipe leaking so I had them all replaced.
The O2 sensors were changed to fix the O2 codes two weeks later along with new Sparkplugs. I used the Bosch 15716, and 15717 Oxygen Sensor as recommended on this site. Purchased via Amazon and they confirmed these sensors are for an 3.0L 2001 S-type.

Correct oil has always been used, Castrol.
Plugs were changed same time as O2 sensors.
Air filter changed every 25K (correct ones used).

Codes stayed away for about two months.

Yes I can get a decent report by clicking the print icon in AE but it prints to an XML format which I had to convert to PNG, sorry about that, but I couldn't upload an XML file.

I do have data from AE in a CSV format if interested?

Mark

 

NO 2 PROBLEMS, OR 1 THAT CONTributed to the cat failure. slow to respond sensors are a sensor fault. Not cats, but slow responding upstream 02 can lead to inefficient cats, cause they dont regulate air to fuel ratios properly.. Or just be 2 seperate problems. the 420/430 cats codes are for inefficiency. This meens that the ecu expects to "SEE" a certain cleaning of the exhaust stream as read by the downstream sensors. If the efficiency goes down to EPA mandated parameters, then you get those codes. The car most oftens runs fine but no longer meets emmissions standards. Hense the cel and codes.
on the bungs..no gblover. these are weld in bungs that are threaded to fit the 02 sensors in where you need them when either building a exhaust system, or using generic non specific cats like what I mentioned with Magnaflo's. You drill a hole where you want them and weld them onto the pipe or cats. Then the 02's thread into them

 

Brutal, thanks.

gbdiver, seems to me that if you replace the cats your underlying problems will damage/destroy the new ones (though who knows how quickly) so you'd be best to fix the problems. When you changed the O2s etc and the P0133 & P0153 didn't go away, didn't you try to find why not? Did you change any of the coils that sit on the plugs? Was there any oil or water in the plug wells?

As you have essentially the same code in both upstream O2s, both of which were replaced, I'd think you're looking for a fault that affects both banks in the same way. Usually an air leak bu in this case I don't know what else it could be. (The usual suspects include the MAF.)

With those codes I expect the car's not going CL (closed loop), but in case it is what are the fuel trims at idle? How steady is the idle?

I can cope with CSV but not sure what to monitor!

 

Update:

Seems I am only getting 420 and 430 codes now. 420 shows up first (interesting) then 40-50 miles later I will get the 430 code too. Nothing about O2 sensors at all.

Coils were not changed, no water or oil was sat anywhere, I have never had a misfire code. Can't remember the colour of the coils, sorry.

Brutal, I have found these CATS, would you mind giving me your opinion on them please?

http://www.autopartswarehouse.com/au...W4aaf53750a46b

THANK YOU.

Mark

 

Those are fine, but you may want to talk to a muff shop about what they can do for a weld in. You may still save more that route vs bolt in

 

Guys, I had P0430, code. Did all the swappings o2 sensors,plugs and coils. It did not fix the problem.I went to local muffler shop, and welded a AIRTEX CAT. Cost was 290/-.He only welded,the bung for the rear o2.Used the original 02 bung in the front.Alas, CEL gone, no codes my wife is happy. I live in CA, and this cat is CA legal, They even provided a certificate.When i inspected the old one it was melted in the middle. my car is 2000 v8,stype

Good luck

 

I ordered two cats from Drivewire.com for $427.00 including shipping and tax, not a bad deal. I had them installed today and there was a little welding to be done to the right side fitting but so far all is good.

I cleared the codes now all I need to do is drive. Fingers crossed.

Mark

 

48 hours into the new cats and all is good. I passed my emissions test and the MIL is still off.

Happy camper here.

THANKS BRUTAL!