Ah, an S40. This was a joint venture platform for Volvo. I was thinking you had a P2, like mine, but this one is a hair different. A four cylinder vs. five, but the same design. Slightly different chassis. Different transmission.
So, forget what I said about transmission.
Don’t worry about suspension.
Good on ya’ for the plugs. If it runs well, it’s worth keeping.
Oil change - get a tool for the filter. This engine has a flat bottom sump, and the dipstick is a straight shot. An oil extractor works well. Change the oil that way for now.
With older cars, the catalytic converter code is often an efficiency code. The ECM is measuring O2 sensor readings before and after the cat and comparing them. If it doesn’t like what it sees, it throws the code. If the code stays gone, with new plugs, great. If not...
Dealer fix is to replace the cat. Let me guess, $1,800? Get an O2 sensor extender, I mean spark plug “non fouler” like this:
https://www.amazon.com/Spark-Non-Foulers-Straight-Threaded-(32mm)/dp/B08D6FDRJ6/ref=yo_ii_pd_dx_gr_1/143-9472358-9057343?_encoding=UTF8&pd_rd_i=B08D6FDRJ6&pd_rd_r=4e4ceaed-3514-41e7-b105-b512864565ec&pd_rd_w=d5HMb&pd_rd_wg=fcsh2&psc=1&refRID=0NKR256Y5J82E09M745J
Install that on the rear O2 sensor, clear the code, and then see what you get.
Cheers,
Astro
So, forget what I said about transmission.
Don’t worry about suspension.
Good on ya’ for the plugs. If it runs well, it’s worth keeping.
Oil change - get a tool for the filter. This engine has a flat bottom sump, and the dipstick is a straight shot. An oil extractor works well. Change the oil that way for now.
With older cars, the catalytic converter code is often an efficiency code. The ECM is measuring O2 sensor readings before and after the cat and comparing them. If it doesn’t like what it sees, it throws the code. If the code stays gone, with new plugs, great. If not...
Dealer fix is to replace the cat. Let me guess, $1,800? Get an O2 sensor extender, I mean spark plug “non fouler” like this:
https://www.amazon.com/Spark-Non-Foulers-Straight-Threaded-(32mm)/dp/B08D6FDRJ6/ref=yo_ii_pd_dx_gr_1/143-9472358-9057343?_encoding=UTF8&pd_rd_i=B08D6FDRJ6&pd_rd_r=4e4ceaed-3514-41e7-b105-b512864565ec&pd_rd_w=d5HMb&pd_rd_wg=fcsh2&psc=1&refRID=0NKR256Y5J82E09M745J
Install that on the rear O2 sensor, clear the code, and then see what you get.
Cheers,
Astro