My shop tells me the computer can only read one problem at a time so after I replace the catalytic converter we may well get another check engine light and the computer could well say we need 02 sensors or something else. Does that sound right to you guys? I'm trying to decide whether to do everything at one time or risk just doing the converter.

 

I just experienced the same thing. I just had my mechanic change the Mass air flow sensor on my 2001 v70 and not 24 hours later the check engine light comes on with a code for a bank 1 o2 sensor. I've been told I can change the sensor myself but I have 2 questions. What's the proper procedure and which sensor do I order? They range online form $80.00 to $200.00. Let me know if you get an answer and I'll do the same

 

The computers read many more than one code at a time.

 

Why does my mechanic say he won't know about the 02's til the converter gets replaced ?

 

Not sure I will put it this way. In the last 6 years I have only replaced 3 cats on the P2 cars.(S60/V70,S80,XC90)

 

So Tech, are you telling me that when they put my car on the computer it can tell them the converter and the 02 sensors are bad as well as possible other things? I trust my mechanic (I think) but you kind of indicate I might be being taken for a ride, so to speak...

 

The computers can hold up to I believe like 50 codes at once. When you read them you start at the #1 code and work backwords. Many things can throw a cat code.

 

In other words if you have a Cat and o2 codes start with the o2 before the cat.