ok so here is my problem. i have a 1998 s70 t5 se. 5 months ago i was getting 420km city and about 500km+ highway. i left the country for a month so the car wasnt being driven everyday, and was only being started twice a week for a quick drive so the battery doesn't die. after i came back i immediately noticed a big difference in fuel consumption. it is now doing 310km city and barely 400km highway. got it scanned , codes were an abs fault and a sas code (p0410). i changed my radiator becuase the oil core was cracked and mixing the oil and coolant. the problem was still there after. thinking maybe it was an o2 sensor i changed only the front o2 sensor. the problem still exists. tune up was done about 9 months ago everything except from distributorcap and wires. plugs were changed. has this happened to anyone and can help me figure this out? its costing me alot of $$$ and i dont want to get rid of the car i love it too much! thanks!!!

 

The PO410 code is for the AIR pump. Check the fuses and listen for the AIR pump to turn on when you first start the car cold.

 

Many things can effect fuel consumption. Tire pressure, ambient temperature, etc. I would replace the rest of the ignition parts if they are over 5 years old.

There is also a few fuel consumption threads in the General Volvo chat & 850 subforms.

 

i read a few of the posts. i read that it could be the thermostat. so i noticed that the temperature doesnt stay at the usual spot. it stays right below. so im guessign the car thinks its not at operating temperature so its pumping more gas to heat up. but the gas mileage is now pretty good on highway. id say even better. did 300km and only used half a tank. so thermostat is next to fix the city mileage

 

Very nice. The computer knew the motor was cold so it was making the car run rich to keep it running smooth.

 

ok so i changed my thermostat the city mileage is still bad only 300km still doing close to 500km on highway which is fine. can anyone help me out to fix this problem!!!!!!

 

kind of a long shot, but have you done a compression test lately? Could be with all that sitting your cylinders became rusty and you have loss of compression. It's really a long shot since it only sat 5 months and it was fired up regularly.

 

Clean the MAF and see if that helps.

 

Use a cleaner for MAF. I was on another site and someone tried to clean with carb cleaner. It will cause the unit to not function correctly.