Oxygen code trouble

[alexander]

So took this '96 Q in when check engine came on.Codes P0150 O2 sensor B2 S1They tested sensors... are working normallycleaned connectionsRoad test without 'check engine light' on.Picked up Q,.....' check engine' light is ONTotally maintained 150,000 milesReturning next week any suggestions?????

[Q45tech]

How many times have O2 sensors [4 units] been replaced they usually function for 100k or 6 years before getting too sluggish.

[alexander]

the O2's were new as of 8 months ago

[alexander]

I believe they only replaced 2 Ox sebsorsI no longer take the Q to Infiniti service in my area they really SUCKso have to depend on my guy who does not bill me for anything they can not repair. They did the Cross/ member and the knock sensors so I need to trust someone. Perfect work.

[maxnix]

Best to replace in pairs so duty cycle tends to match.

I presume it is the rear driver's side one? Get OEM from Joe or call sparkplugs.com and order the correct ones. Webpage is not always accurate, and I think NICO gets a discount.

[Marv007]

Alexander, I am no expert but I can share my experience with O2 sensor codes. I purchased my 96Q out of state with 82K on it Aug. 2007. When I needed knock sensors, and O2 sensors per my chenck engine codes I did a full ultimate under plenum hose kit at the same time. Cleaned everything per this forums suggestions. It ran seamingly perfect and with Goody's help I was able to get the check engine light to finally work correctly and got the Q smogged. The weird thing was that I didn't change the O2 sensors but the codes didn't reappear for a while. About 3K miles later the sensor codes came back but a mechenic told me the bad sensors would mainly affect milage and I was getting 20.5- 25.5 on the highway anyway. My Q was running so smooth and strong with a 600 RPM idle at rest that I just kind of let it go and focussed on some other things. I just occasionally checked the codes to make sure there was nothing new even though the car was running great.

Sinse I had just had it CA smogged I took it to a muffler shop and had the suitcase removed and went with straight pipes out the back. I will add small mufflers in the future because it scares people when I let it breath merging onto a freeway. There had to be 1.5 gallons of water in that muffler that was removed; unbelievable! But here is the weird part; the O2 sensor codes went away immediately and didn't return for the next 15K miles. I just use injector cleaner every 3rd tank of gas.My codes came back briefly on a 700 mile trip to Seattle last summer as I passed through Oregon. I added injector cleaner and the light went off until I passed through Oregon again on the way back. Even wth the light on for the sensor codes I got 25.6 MPG for over 450 miles.

In summary, My Q purrs at Idle and flat out rips at full throtle with the same O2 sensors that had ever thrown any codes. In the old days cars needed the carbon blown out on occasion and I think these Q's do too. My Q has 101,800 miles on it now and I just enjoy the hell out of merging onto freeways for a few miles occasionally. Drop the suitcase and let it breath once in a while. Works for me.

[alexander]

Hey thanks for the advice!!!The Q runs great even with the check engine light on. When the knock sensors code came up earlier this year I did the 'works on the car' like 3 grand worth. Knock sensors, O2 stuff all the hoses etc.So I'll take it out today and try not to outrun CHP. I think your right about the codes coming up and then disappearing.

[maxnix]

Drop the suitcase and let it breath once in a while. Works for me.

Another false assumption that the rear muffler is somehow restrictive and impedes exhaust flow. Being stainless steel, I wonder how long non SS stright pipes will last.

If you truly get 25.5 mpg, you have the most efficient VH45DE ever made.

[Marv007]

I don't think the suitcase is restrictive but removing it with all the water build up sure seemed to impede the O2 sensors from throwing codes. Very likely just a coinsidence but why all the water in the muffler?

[qship96]

Muffler has nothing to do with o2 sensor or throwing the codes,as it is DOWNSTREAM of all 4 o2 sensors. Water buildup is just condensation, proving the car is not driven at high speeds for extended length of time{highway} regularly, which would have heated up muffler enough to burn off the moisture.

[Marv007]

Pretty weird huh! I wonder if the water could actually increase the detected conditions the sensors were reading. Probably not because that would mean there was some back preasure created by the suitcase full of water. I'm just glad the codes went away when the suitcase did. Saved me alot of money.

[Q45tech]

Measure the back pressure after last O2 to see how much if any power you are losing. Each psi is ~1.0 [+- 0.1] Hp.

I enjoy watch the jaws drop when owners see there is no measurable [<1 psi] back pressure at idle > 2,000 rpm cruise..........obviously the back pressure is a direct function of intake air flow and rpm. Things do start showing up after 4,000 rpm and WOT.

The loudest most offensive exhaust known to man [no rear mufflers and only straight thru resonators] cannot improves things by even 10 HP.

Even money is no object [rear mufflier cost ~ $1,000] teams of engineers can do wonders.

One learns alot when you drive the same vehicle for 20 years. My greatest experimentation days were back in 1992-94 [I spent $6700 on extra performance goodies] before I took the Q back to Grad School.

The ecu, tcu, sway bars, springs are still on 16 years later.

The loud exotic $1400 exhaust rusted out in 7 years and was replaced with a low mile 1995 oem system from a junker.

I really enjoy seeing people distroy lux car fast as that leaves me lots of parts for cheap.

[alexander]

problem solved by tightening a loose air intake boot. Q runs great now! No charges for all that work. Check engine light stays off.NOW,Having performed right now a BG trans fluid exchange on the recently purchased '06 Lexus LS 430.(50k miles) The so called sealed system 'never needs changing' 'according to Lexus service tech.'My tech found the fluid going through the BG machine looks like chocolate syrup. Running BG twice. None too soon I hope.

[maxnix]

You did what you could to prolong its life. At only 50K and it was brown? Maybe the OEM ATF starts out brown?

[alexander]

My service tech said the ATF fluid that Lexus/Toy uses is not the greatest, let alone gas pedals. The newer Lexus' '07'-10' are a different animal and NOT better than '05/'06's. But my '06 LS is like driving a refrig. Love my Q. It will get all the $$ it needs!