Hi All,

Looking for collective knowledge/experiences on this one. Here's the story:

1995 850 20Valve N/A; approx 160K miles

A few weeks ago i get a CEL; DTC is 1-5-3 which is "Rear HO2S Signal". So I replaced the rear Heated O2 sensor; OEM Bosch from IPD. But note: when i took the old sensor out, I noticed a couple of the sensor wires had worn through the insulation, up near the connector, from rubbing on the frame/chassis (not routed correctly). I considered just repairing the insulation and reusing it, but I had already bought the new O2 sensor and figured it was probably due anyway so I went ahead and put the new one in.

Within a couple of days the CEL comes on again; this time it's two codes:

4-3-5: Front HO2S Slow Response
4-4-3: Three Way Cat Converter Efficiency

So has anyone experienced this before? I almost tempted to put the old rear sensor back (repair the insulation) in and see what i get.

Yeah, it's possible i need both O2 sensors and a new CatConverter at this mileage; just seems a bit strange all this happened at once.

BTW: For more detailed info on what these codes mean, found this great post:
http://www.volvoforums.org.uk/showthread.php?t=8600

Appreciate any input/suggestions.

Also any experience with replacement CatConverters? FCP sells this one for $250; MFG is Davico; anybody know if this is OEM?

Thanks again!

 

sounds as though maybe both o2's were just fine, but the cat is bad. realistically if you threw codes for both o2's there is only one thing in the middle messing with it, the cat. i say you need to replace your cat.

now as where/what to buy i have no idea, so that up to the other guys

 

Has anyone replaced their cat converter? Where did you get it? What was your experience?

Thanks!

 

Front O2 slow response means the sensor is bad. The second code basically means if you wait to long the cat will go bad.

 

Thanks for the input tech; looks like another O2 sensor is in my future...

I would still appreciate any experiences/knowledge regarding the cat converters though...

1. Does cat generally need to be replaced after so many miles, or do you wait until you see symptoms or codes that point to the cat being bad first?
2. Do cat converter usually get more restrictive (flow wise) with age/mileage, or less?
3. Any feedback regarding aftermarket cat converters?

Thanks!

 

1) i usually just know when i start to throw codes and such.

2) they clog, so yes.

3) to be answered.

 

I have heard that like spark plugs, Volvo's are finicky about O2 sensors and seem to prefer the OEM ones. Just my .02 for when you replace the front one

 

I do not see many cats that go bad. Aftermarket ones tend to make the exhaust louder.

 

nothing wrong with that

 

Just want to say

Thanks again Tech!

I replaced the front O2 sensor (OEM Bosch from IPD) a week ago and no more DTCs! Seems to run a bit better too. So looks like my cat is good for a little longer yet...

Thanks for everyone's two cents!

 

Glad all is good.