Recently (4 days) purchased a used 2000 V70 XC. Interior in tip-top shape, and in fact the cleanest used car I have ever seen. Engine in very good condition, especially given mileage on it (155K). It was given a clean bill of health by 2 inspections prior to purchase.

Put in about 10 gallons of gas the day I bought it, and it ran fine for about 150 miles. Then, all of a sudden the CHECK ENGINE light comes on while I'm driving it. Everything looks good - the rpm's, temp, etc - and drives fine also. I get somewhere to check it & they tell me it's one of the oxygen sensors.

I also checked to make sure it's not something stupid (gas cap, etc). When I ruled that out, they asked what octane level I used in it.

When I bought it, I stopped at the closest station (a Sheetz station), and put in 87 octane gas - the same type I put in everything I own. The place I had the sensor reading checked suggested putting some octane booster until I was able to run out the 87 in the tank & then try a higher level (89 or 93 octane). They reset it, and I did add the booster and it hasn't come back on, but it's only been driven a few miles.

I'm new to Volvos, but have owned VW's (87 Jetta) and Toyotas (93 Corolla) for over 20 years. A friend who owned Volvos (he drives an 84 sedan) hasn't had issues with gas octane levels.

• Are Volvos, or V70's in particular - this sensitive to octane levels?
• Is this an issue that's more connected to the ethanol that they put into everything now, and is there any remedy to it?
• Or, is this just something I'm going to have to bite the bullet on & replace the O2 sensor on a car I've had less than a week?

 

Sorry, but the gasoline octane doesn't have anything to do with your o2 sensor codes. It's not uncommon for oxygen sensors to go out on this model. It's also not uncommon for the flange on the catalytic converter to crack and set fuel trim codes due to air entering the exhaust stream. Is the code specifically for the o2 sensor or is it a fuel trim code?

 

I've not seen the code personally myself, and it's been reset.

Is there a way to tell what the last code(s) was? All I know was they said it was the O2 sensor.

 

I had a 99 V70 with CA Emissions: Go get a new gas cap, and have the computer reset. The problem is the emission system is detecting a leak in the fuel system evaporator. The cap was the issue with mine, and Volvo service told me it's a sensitive system.