Hey everyone out there in the volvo world just an average Jo who does his own repairs in need of some wisdom and direction. I've got book for you to read first tho...

it was a dark and lonely night... " P2188 - Fuel system too rich at idle bank one" illuminated on the scan tool.

the car was running fine so i left it until after i did some other repairs - broken coil spring on front strut / front brakes.

I did some research in the mean while on the various forums, deduced that it was an Oxygen sensor (O2) sensor code.

so... knowing that O2 sensors are pretty costly I purchased both upstream and downstream sensors from FCP euro - an exact fit for my 2004 s60 2.5T AWD .... or so I thought ...

Had to bring it to a shop for an immediate fix -( ball joint fell out of the bottom of control arm), had them check the code - told me it was an O2 code. I was going to have them put the O2 sensors in while they had it but they told me they weren't the correct sensors (one was a V70 and the other was for something else) (based on them checking the part numbers through Napa autoparts). So I had them not put them in.

Disappointed with this I later went to Autozone, I had them order OEM Bosch sensors. upstream - i think was 17373(?) - they said that DENSO was the OEM manufacturer. Which they offered again 2x the cost
where the napa one was 2X the cost - they said Bosch 17070 (?) was OEM & that those were the ones put originally into volvos.

*I disconnected the battery to reset the codes - reconnected after installations were complete*

Up - Stream
Turns out the one i got online upstream (on exhaust manifold) was the same - bosch 17373 - put it in, everything went in great. found that wires melted on the manifold - came out of a wire path holder (plastic c clip thingy). - took the heat shield cover off of the old wire with burn spot and rigged it up on the new wire just incase it comes out of the C clip thing again.

Down - Stream (Catalytic Converter)
Put the OEM Bosch from autozone in - the one i got from FCP euro was the wrong one - wrong length. i'll try to get the part numbers up this weekend.

car started rough but after it was on for a bit - idle was better. The Miles/ Gallon reading was accurate also instead of way off like it had been (on the dash) . Check Engine light came on 3-4 key cycles, a few short trips later.

now i had 4 codes come up
p0140 - O2 Sensor Circuit No activity Detected Bank 1 sensor 2
P0141 - O2 Sensor Heater Circuit Bank 1 Sensor 2
p0030 - HO2S Heater Control Circuit Bank 1 Sensor 1
p0036- HO2S Heater control Circuit Bank 1 sensor 2

So I checked the forums - someone else had this problem after they put a bosch sensor in also, turns out that a 20A fuse in the engine compartment was blown (O2 sensor heater). So i put the spare 20A fuse in and drove on.

Light never went off after a week or two of driving. Erased the codes. Light came back on after 2-3 short trips.

NOW:
the new code is the same code that I had before P2188 - Fuel system too rich at idle bank one - and my vehicles mpg reading is way off again telling me i have an average mpg of 36 (18.3 actual)
Similar to before changing any sensors - the vehicle has a hard start most of the time also

From what i understand is that
1)my car being the typical strait 5 cyl - only has 1 bank
2) up stream (exhaust mainifold) sensor is the a/f mixture / fuel altering sensor with 6 ports - heated sensor
3) down stream (cat sensor) just calculates if it's rich or lean - 4 port sensor - also heated

RECENT MAINTENANCE
In last 10k miles

all injectors replaced - misfire code
All spark plugs replace - misfire code
coil on plug cyl 3 replace - cyl 3 misfire code
Fuel filter
air filter - replaced last month

have not done pcv system (oil canister)- but checked check valve (under intake manifold) - very clean
the pcv nipple on the air intake tube (near turbo connection point) is very clean

Sorry for the book guys but as you can see this is a bit tricky for me. Wondering if anyone can give some advice/ direction.

spoke with someone recently about adding a spacer (??) to the sensors and maybe the sensor height was off?

I thought this sounded weird, as i have new sensors in but yet the SAME original code

Thanks for your time gents!