rear 02 code now a map sensor code

lhailah · Post by **lhailah** » 24 May 2012, 12:47

So I've had a rear o2 sensor code on my 98 xc70 for sometime now. Before going to replace the sensor I checked again and had some misfire codes along with the rear o2 code. (i installed cap and rotor and new plugs less than 4k miles ago so those are fine.) So I change the sensor with the bosch part(my only sensor was dogged I doubt it even worked) then check the codes again. I still have the rear o2 sensor code and then pulled a p0108 code. the misfire codes went away on their own it seems but advanced auto no longer clears codes so i wasn't able to clear the codes and check again.
I bought the MAP sensor and came here looking for pictures on where to locate it but instead i'm reading that I don't even need it.
Any advice?
is the rear 02 code just a stored code that needs to be cleared? Should I install the map sensor? How do I locate it?

Post by **jblackburn** » 24 May 2012, 13:36

That MAP sensor code will haunt you with a damn check engine light every time you turn it off.

Replace it, but it probably has nothing to do with the O2 sensor code. Which code number are you getting?

The MAP sensor is on the end of that pink plug.

lhailah · Post by **lhailah** » 24 May 2012, 13:56

ok so when I originally pulled the codes I was low on oil because of the bad dipstick and we have just powerwashed the engine to find the leak. the codes were. 0300, 0136, 0301, 0333, 0304, 0302, 0303, 0141, 0305 and 0302
since changing the o2 sensor i have code one of those o2 sensor codes as well as the p0108 which is new. unfortunately I did not write down which o2 sensor code that came up because i assumed it was just a code that needed to be cleared. it was either 0136 or the 0141
I read on the obd site that the map sensor can give a rough start, lower fuel milage decreased engine power or no start. How true is it about fuel milage? I'll replace it if I will get more miles per gallon. I feel like the car isn't starting as smoothly as it had been before I changed the o2 sensor yet that could just be in my mind...

Post by **jblackburn** » 24 May 2012, 13:59

Misfire codes were most likely from washing the engine; I wouldn't worry about them.

The MAP sensor really doesn't affect anything in the way these cars run (at least not until the S60 models). My engine light always came on when I got back around sea level and went off when I went back up to 3000-ish feet.