1998 v70xc MPG difference w/bad cat &/or 02 sensor

[matthew1]

... but I'm thinking I might need to replace the cat due to the damage it has sustained thus far with the o2 condition.

I'd be very surprised if this was necessary. Very rare to replace the OEM cats. They're very durable.

A bad O2 sensor always kills mpg on these P80s. I've done this dance twice. The first time my 850's mpg went to 12 IIRC.

[shiloh51933]

... but I'm thinking I might need to replace the cat due to the damage it has sustained thus far with the o2 condition.

I'd be very surprised if this was necessary. Very rare to replace the OEM cats. They're very durable.

A bad O2 sensor always kills mpg on these P80s. I've done this dance twice. The first time my 850's mpg went to 12 IIRC.

my 850 barely lost mpg when front/ back o2's went bad.

[precopster]

Last week I had a 99V70 na in for an ETM repair. It was a new purchase for the owner and he had throttle codes & O2 codes. Car only had 140K kilometres.

Once I replaced the throttle the O2 code stuck around, even after a decent highway drive. Having a Denso O2 sensor in stock I changed it out. After 30 mins the O2 code returned. Finally after an adaptives reset I got a coolant temp sensor code. Coincidentally I had been monitoring coolant temps at between 72 degC and 101 degC which were all over the place. Sometimes while warmed up it would return way back down to 75 deg C. Also with coolant temp at a low 70 degC the coolant fan started running when key was turned off-classic ECT behaviour.

Changed out ECT and thermostat with a Wahler and O2 finally disappeared. On the way home the engine light re-appeared for the customer. By this time he was pretty fed up. It was a MAF code. Connector for MAF was cleaned and no codes have returned.

The point is sometimes a combination of faulty or dirty components can point to O2 sensor. I doubt his O2 was faulty but with 2/3 of its lifespan spent the owner decided to keep the new one.

[shiloh51933]

Thank u precopster...i knew this car needed work but your right. Anyway i found out why front o2 is original...somebody stripped it. My snap on wrenches couldnt even grab it...o2 sockect 1/2 drive is missing, could only find 3/8 drive o2 socket. this sucks!!

[shiloh51933]

What a difference in MPG's...I do quite a bit of driving with this car for work and I was getting killed aat the pump, especially buying 93 octane!

[shiloh51933]

Last week I had a 99V70 na in for an ETM repair. It was a new purchase for the owner and he had throttle codes & O2 codes. Car only had 140K kilometres.

Once I replaced the throttle the O2 code stuck around, even after a decent highway drive. Having a Denso O2 sensor in stock I changed it out. After 30 mins the O2 code returned. Finally after an adaptives reset I got a coolant temp sensor code. Coincidentally I had been monitoring coolant temps at between 72 degC and 101 degC which were all over the place. Sometimes while warmed up it would return way back down to 75 deg C. Also with coolant temp at a low 70 degC the coolant fan started running when key was turned off-classic ECT behaviour.

Changed out ECT and thermostat with a Wahler and O2 finally disappeared. On the way home the engine light re-appeared for the customer. By this time he was pretty fed up. It was a MAF code. Connector for MAF was cleaned and no codes have returned.

The point is sometimes a combination of faulty or dirty components can point to O2 sensor. I doubt his O2 was faulty but with 2/3 of its lifespan spent the owner decided to keep the new one.

I got rid of o2 codes, MAF code, wastegate solenoid code, SAS code, misfire codes and of course I get another CEL P0442 evap

[abscate]

P codes are just the way your Volvo says "Im beautiful..love me..."

[shiloh51933]

P codes are just the way your Volvo says "Im beautiful..love me..."

Real cute...she's gettin' plenty of TLC!!