I'm thinking about purchasing an '01 S40 with 80k miles from a friend for my college-aged son. However, it will need a couple of repairs. When she took it in for emissions testing, the codes PO 420 and PO 128 came up. She took it to a shop and they said it needs a front catalytic converter and coolant temp sensor. Any idea on an average cost for these repairs? What do you think is a fair price for the vehicle taking the repairs into consideration? She gave me the paperwork from the shop and is someone I know and trust. Neither of us know much about cars. Smart women, cars... not so much.

 

As an owner of a 2001 with 175k miles I've seen these exact codes. What I would do: Depending on how well you know the seller you can ask for a large discount because replacing the cat convertor and CTS is very expensive at the dealer (true enough). However, in reality you most likely have a bad lower O2 sensor and a bad thermostat. Total cost for the home mechanic is less than $100. Those are very easy repairs too. Don't forget a new gasket with a new thermostat.
Buy Stant Thermostat, 195 Degrees Fahrenheit 13379 at Advance Auto Parts
This should be the lower O2 although it does not specifically list it.
Buy Bosch Premium Oxygen Sensor 16292 at Advance Auto Parts

An even less expensive option is to use this part instead of the new lower O2 sensor (or in addition to a new O2 as I did)
Oxygen Sensor Spacer (CEL Boss)

 

Thanks so much! I was looking around at repair costs for those codes and replacement and it wasn't looking good. ($1,400 to replace front CAT?). I did some research for my area and found that this make and model in it's present condition (not including necessary repairs) is about $3,900. We looked at the paperwork from the shop and the vehicle values together, so now just need to figure out a fair price. I really like this car for my son. Volvo's are solid, dependable and go for miles & miles. He needs something he'll be able to drive over the mountain pass to college and back. Again, thanks for the reply. Any other insight is greatly appreciated. Need to make an offer in the next week or so. Thank you!

 

They are very safe and there are forum members here who've been through terrible accidents and walked away. My 16 year old daughter drives my 2001.

They are not without need for TLC however. You will also need a timing belt at 100k miles and that can be expensive if you go to the wrong shop. Read the faq here and alot of what I'm writing about will be explained.

 

I have those same CEL codes and I just replace the thermostat every three years. The CEL goes on for catalytic converter every winter when they change the gas formula over to the winter blend. A few tanks later and the light goes off. The cat can be bought on eBay for under $200 and is really not that tough to replace but I would replace both O2 sensors first (I'll be doing this shortly - Thanks Hudini). With that mileage I'm thinking it's worth closer to $3000 especially with those repairs.