o2 sensor problem..

[DrivingMyQ45IntoTheGround]

recently i had some issues with my q45 throwing codes. cleared them all up, the last part being to replace my rear o2 sensor heaters.. so i swapped them out with no problem what so ever. checked the connectors and the harness. plugged 'e, in and presto ! no more codes, that is until i hit about 48 miles of use on them. then they started throwing codes again. recently the FSM has been my bible and i have attempted to research as too what may be the issue. and i am starting to think that possibly the codes being throw have to do with something else. the harnesses are good.. one connector was slighlty corroded so i cleaned it up..but still throws out the dtc p0141-p0161 codes.. any suggestion out there as too what may be a seperate underlying cause ?strange thing was this.. at the 48 mile mark i had returned back home and , was congragulating myself on a job well done when i decided to swap out a faulty boot on my ingition coil.. that being done i started the car up and the SES light was on.. and it was at that time the codes popped up.. could there be a connection? or just the simple fact that i turned the car off. ( i knew i should have just driven the extra 2-3 miles to build up a enough history to get the damn thing smogged..)

[Q45tech]

It is not just a certain number of miles but a SPECIFIC COMBINATION of starts, warm up and cool down cycles, miles and rpms. All explained in FSM.

Since their are 4 combustions per engine revolutions [on a V8] ~50 miles might be ~ 1 hour or 3 hours. At steady 2000 rpms [8,000 combustions] say 1 hour...............hopefully you can see how slow to warm up sluggish O2 affect things.

[DrivingMyQ45IntoTheGround]

thats what i dont get, i understand 90% of what you are saying., must be the noob in me,

i swapped out the o2 sensors and the codes are still being thrown. same codes, nothing has changed..ecxept for the new sensors of course

[maxnix]

Start with this recent thread for the front end.

zer...-help

[DrivingMyQ45IntoTheGround]

i guess i had that coming thanks i needed that !

next time i have a engine sieze on me i will make sure to check my tire pressure ! jk...

[Q45tech]

One thing that confuses some is the almost bullet proof nature of the 90-93 Q45 cats. Every subsequent year they got thinner and thinner, less obscenely expensive platnium in each one.

The result has been many cats weaken and then finally fail after 10 years of operation....................................some of the post 2002 units barely last thru epa 85k warranty most are pretty flakey by 70k.

[DrivingMyQ45IntoTheGround]

interesting indeed, i didnt realize that.. one thing that really amazes me out here in california is the smog laws.. hell i pass the emmissions with flying colors, its the damn MIL that is killing me..

can of gasoline, match, cigarette, final solution..

[loystock]

[QUOTEi swapped out the o2 sensors and the codes are still being thrown. same codes, nothing has changed..ecxept for the new sensors of course

[/QUOTE]

Code P0141-P0161 covers both left and right banks and front and rear sensors. So what was the original fault code and which sensor did you replace? The post above and the original one are a bit confusing to me. When you swapped the O2 sensors, did you get the same code or a different code - e.g. a defective HO2S2 Left Bank with P0141 code when transferred to the Right Bank may trigger P0156.

[DrivingMyQ45IntoTheGround]

original fault codes were P0141 & P0161, and indicated b1s2 and b2s2, for my rear o2 sensors.. so it was both rear sensors i exchanged out with new sensors..now both codes still pop and also now throwing a P0136 ( possibly PO0156?) fault code..since yesterday..which puts me in a total quandry as too how to proceed here.. sorry for the confusion about the post..

my Q also seems to be throwing out random codes ( nothing repeated or listed as 1t on the code scanner) since this whole drama began...so i finally bit the bullet and had her taken to the shop... should hear today as too where the main problem lies, seems to be electrical issues..who knows? the only thing i do know is that it is gonna get pricey. so worse case scenerio gonna part her out.

[loystock]

If you are getting random codes, it could be due to a failing alternator (unstable voltage from internal voltage regulator or defective rectifier/diode). The charging voltage from a good alternator should be 14.1-14.7 VDC. A low or excessively high charging voltage from the alternator can give all sorts of problems. Alternator can also fail due to a weak battery (a good battery must have >12.5 VDC with engine OFF).

[DrivingMyQ45IntoTheGround]

good call loystock, thanks for the advice.ended up working on it with my friend at the shop over the weekend. ended up being a bad connection in the harness, so we replaced that, put in the correct fuse ( 7.5a as compared to 10a) and the codes were cleared up.. bench tested the old o2's to see if they were actually good to begin with, which they were not..then proceed to test the alternator, A+ & good to go so we dropped in a new battery with the proper requreiments to meet or exceed OEM..

seems a few of the "random codes" are not so random at all, i have connection issues within my wiring system that we are disecting one by one..it is like pandoras box.

"step by step and inch by inch i lept from plank to plank, who knew that the last leap would be my last. thats i where i got this little limp, that some call experience"....