How do I tell the difference between a bad O2 sensor and a damaged catalytic converter?

[crazytooguy]

1998 V70 GLT - the turbo was leaking oil into the intake, so I took the turbo off and had it rebuilt. Now that's all back together, I get codes for the O2 sensors - sensor 1 slow response, and rear O2 sensor compensation. What's a good test to determine if the O2 sensors are bad, or if the catalytic converter is damaged from all the burnt oil that was going through it? I haven't driven it much since the turbo was replaced, so will getting some highway time help?

Thanks!

[kallekula]

Measure temperature of exhaust pipe before n after cat. If cat is working the trmperature after the cat is significantly higher.

[Clemens]

Measure temperature of exhaust pipe before n after cat. If cat is working the trmperature after the cat is significantly higher.

Really? How come? Does the catalyzation process heat uo the exhaust fumes?

I always thought that if the temperature in front of the cat is significantly higher than behind the cat it indicates a clogged cat because the exhaus gases can't be pushed through the cat fast enough.

[jreed]

I had the slow response code recently on my '97 855 GLT and replacing the front O2 sensor resolved it. In your case since you had to remove the turbo I'd recommend double checking the intake system for leaks if you haven't already done that... if you have an intake leak it could cause the slow response code.
Some additional info here: https://www.matthewsvolvosite.com/forum ... hp?t=28754

[abscate]

Cats rarely go bad so if the OXS are over 100k old, do them first. Unless you were blowing pathological oil smoke I doubt the cat is bad

[scot850]

And you would likely get that lovely smell from the tail pipe as well!

Neil.

[kallekula]

Measure temperature of exhaust pipe before n after cat. If cat is working the trmperature after the cat is significantly higher.

Really? How come? Does the catalyzation process heat uo the exhaust fumes?

I always thought that if the temperature in front of the cat is significantly higher than behind the cat it indicates a clogged cat because the exhaus gases can't be pushed through the cat fast enough.

The material inside the cat gets very hot. Exhaust gasses passing through a functioning cat picks up that heat.

[xanthefin]

I did kill a cat when i did modify ECU pretty quickly if that ever happened and tried do tuning on my previous car.

Insides of cat did make 180 degree turn. Otherwise tuning is fun thing.

To back to thing there is good videos how diagnose these issues. Like measuring pressure before and after.. sometimes you can swap first and second O2 sensors to try if fault moves to other one.

[ZionXIX]

I drove around with a turbo oil leak for over a year with no lingering catalytic effects. The was over 10 years ago. I had a 007 style smoke screen everytime I floored it. The volvo version of coal rolling.