Check Engine on, computer codes 443 & 435
 

Hello everyone.

I have a '96 Volvo 850 GLT sedan, with just over 210K miles on it. I am not the original owner and have had it for about 6 months. Very nice car so far.

I got a check engine light, and I had the dealer diagnose the problem: they reported DTCs 443 (cat converter efficiency, according to them) and 435 (front O2 sensor, according to them).

They recommended "replacing both O2 sensors to start".

What doesn't make sense to me is: why replace the rear O2 sensor if no trouble codes are found for it? Don't the codes they found indicate the need to replace one (front) O2 sensor and the cat converter? The job is kind of expensive, so I'd rather not go on a guessing spree...

Any thoughts?

You can try to replace the front only. But if the front is bad the rear is most likely not far behind.

Since I'm fairly new to owning the 850, can you tell me what are the most critical issues to look out for?

The dealer told me I have 68K on my current timing belt, and it's due for replacement at 70K, so of course I will be having that done soon.

But what else should I be on the look-out for?

Check and see if the dipstick tube smokes like a train with the car running at normal temp.Pull the dipstick out with the car running and see what happens.

Thanks
 

I will try that next time - what would this indicate? I heard of this test for diesels, but I haven't heard of this for gassers...

Clogged PCV system.